Telecom Tigers

IPv6 Features !!!

2020-02-24T21:55:00.000+05:30

Hi All,

Greeting from TelecomTigers Team,

Today, let discuss some features in IPv6, which makes it differ from IPv4,

Below are some basic information for IPv6,

Its a 128 Bit Address
Divided into 8 Segments
Each Segment is of 16 Bits
Each Segment is separated by ":" Sign
IPv6 Address Example - ACDF : 0A39 : 412F : B5E2 : 00FF : FF21 : 79EA : 0001

Features :-

Longer Address Range - 2⌃128 Bits (3.4 x 10⌃38 Addresses)
No Broadcast - It has (Unicast, Multicast, AnyCast)
Single IP can be used by specific user at all places i.e. no need to assign new IP every time, as user changes his location,
Single IP can be used for End to End Connectivity i.e. NAT feature not required
IP Security (IPSec) - Optional but Available
Quick Routing - All important information is at starting of Header which help in quick decision for routing
Reduced Complexity in Header w.r.t IPv4,

IPv6 - Address Length (40 Byte with 8 Fields)

IPv4 - Address Length (20 Byte with 13 Fields)

Comments are most Welcomed,

ChEeEeEeRrRrSsS...

Telecom Tigers Team

For Clean & Green Future !!!
http://lightenmyways.blogspot.com

IPv6 (Internet Protocol Version 6)

2017-01-31T16:04:00.001+05:30

Hi All,

Greeting from TelecomTigers Team,

Today let discuss about IPv6 Protocol Overview,

As we all know, that currently millions/billions of users are connected via Internet around the world, & there is continuous growth of Internet usage in Future too, which includes connection of various devices like mobiles/smartphone, vehicles, other devices, etc., which requires more n more unique IP's,

but there is certain amount of Unique IP's i.e. 2⌃32 Addresses (4,294,967,296 which is around 4 Billions Addresses) available with current IP Version i.e. IPv4 (Internet Protocol Version 4 which we normally call as - IP),

So, as the User Devices are Increasing day-by-day, we are running out of these unique IP's, & hence we need some other way & to overcome the issue, before all IP's are Utilized, our researchers came up with IPv6 i.e. Internet Protocol Version 6.

Note :- Its NOT a New Protocol but a New/Modified version of IPv4 (which was having limitation of Unique IP's).

In IPv6, we have Overcome the limitation of Unique IP's by Increasing it Bits Limit from 32 to 128 i.e IPv6 has 2⌃128 Addresses (3.4 x 10⌃38 Addresses), & also making it Hexa-Decimal which overall makes longer address location,

lets see some comparison between IPv6 over IPv4,

Advantage of Using IPv6 Over IPv4,

Provides More Addresses w.r.t IPv4.
Supporting Growth of Internet.
Provides Better Security.
Better Handling of IP's for All Devices.

Comments are most Welcomed,

ChEeEeEeRrRrSsS...

Telecom Tigers Team

telecomtigers@gmail.com

http://lightenmyways.blogspot.com

Roaming Call Flow

2016-10-14T15:10:00.000+05:30

Hi All,

Greeting from TelecomTigers Team,

As per request from many of our readers,
Here is a MT Call Flow, When Subscriber is in Roaming,
Following parameters are not taken here for simplicity i.e. Authentication, Ciphering, Paging, etc.

Postpaid Subscriber MT Call Flow :-

Mobile (MS A) dials Mobile (MS B) Number (which is of Circle 2 but currently in roaming at Circle 1).
"Connect" msg is sent from MS A to MSC A, which analyse B-Number & found it's of different circle, so it route the call to GMSC A.
After receiving IAM from GMSC A, GMSC B initiates the SRI request to HLR B.
In Normal Scenario, i.e. Postpaid MT call flow, GMSC B will initiate the SRI query to HLR B & HLR B will ask for PRN from MSC B (in which MS B currently present), & MSC B will respond to that query by providing MSRN number to GMSC B via HLR B, but here,
Since MS B is in Roaming at Circle 1, so HLR B will ask for PRN from MSC C, via GMSC B & GMSC C.
MSC C provides the MSRN to GMSC A via GMSC C & GMSC B
After receiving MSRN by GMSC A, MSC A routes the call to MSC C.
Now, ISUP msgs (IAM, ACM, ANM, REL, RLC) is sent from MSC A to MSC B, to complete the call.

Comments are most Welcomed,

CheeEeEeRrRrSSS...

Telecom Tigers Team

telecomtigers@gmail.com

http://lightenmyways.blogspot.com

IMS (IP Multimedia Subsystem)

2014-06-09T16:19:00.000+05:30

Hi All,

Here is an introduction to upcoming technology, which is set of standards, developed by the wireless standards body 3rd Generation Partnership Project (3GPP), for providing IP based multimedia services including IP telephony.

It creates new opportunities for operators who want to deliver attractive, easy-to-use, reliable and profitable multimedia services – including voice, pictures, text and video, or any combination of these – with existing services.

IMS addresses key issues such as convergence, service creation and delivery, service interconnection and open standards.

Access-Independent: it is open standardized way to deliver IP-based consumer and enterprise services, enabled by one common core and control, to the fixed, mobile and cable communities.

When implemented according to agreed standards, IMS enables operators to mix and match equipment and applications from multiple vendors, and enables mobile users to access their personal set of services wherever they roam, whichever operator network they are connected to.

IMS includes the tools and functions needed to handle numerous non-standardized services in a standardized way – ensuring the interoperability, access awareness, policy support, charging, security and quality of service functionality required to meet consumer demand for attractive and convenient offerings.

IMS is not intended to standardize applications, but rather to aid the access of multimedia and voice applications from wireless and wireline terminals. This is done by having a horizontal control layer that isolates the access network from the service layer.

Users Benefits:-

• All services, such as voice, video, SMS, conferencing, IPTV etc. will be available on the device being used. This will provide user with rich media experience.

• Safe and secure communication.

• The users will be able to personalize their communication need, such as preferred medium of communication depending on, who is calling etc.

• The use of Internet technologies will allow a seamless communication irrespective of user’s location and the platform of communication

Service Providers Benefits:-

• Use of IP backbone by IMS will provide an optimized transport and coding.

• IMS provides a common standardized platform with reusable components for development of new services. This will reduce development time and allow roll out of new multimedia services quickly, as per the market requirement.

• Quality of service (QoS) has been as issue with IP services. The IMS has been designed keeping in mind quality of service (QoS) requirement, so that the guaranteed bandwidth requirement can be met.

• IMS allow flexibility in charging users as per the services utilized by them.

• The open standards used by IMS allow inter-networking and interoperability between various service providers. This enables them to provide seamless communication to user irrespective of network he is in and the device he is using.

• The open architecture, available common services and converged IP backbone will reduce system complexity, thereby bringing down the CapEx and OpEx for the operators.

• The IMS design has been done keeping in mind operators & allows operators to deploy third party developers for developing application without losing the control of their network.

Main Nodes of IMS System:-

The Call Session Control Function (CSCF) and the Home Subscription Server (HSS) are the essential nodes in the IMS system.

The IETF (Internet Engineering Task Force) Session Initiation Protocol (SIP) is the control signaling routed by the CSCF.
The HSS provides the user profile database to manage user authentication and authorization for the subscribed services.

More Information will be Updated Soon....

Comments are most Welcomed.

CheEeEeRrRrRsSsS...
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

How GPRS Works

2014-04-02T16:27:00.000+05:30

Hi All,

Lets have some details regarding GPRS Working, As we all know, It’s a Packet Switched Network,

In a GPRS Network, a user station doesn't occupy a dedicated path during an Internet connection. However, each end user station (e.g. mobile phone) is allocated several time slots out of 8 GSM/TDMA available time-slots for GPRS service.

Each time slot has a maximum capacity of 14.4 kbps, depending on how many time slots are allocated for the downlink (from a base station to a user station) and the uplink (from a user station to a base station),

GPRS devices are divided into multi-slot classes. A multi-slot class is often represented by the number of downlink and uplink slots. For example, Class 10 is also known as Class 4+2. While active slots indicate the maximum number of slots that can be allocated for both downlink and uplink in a specific class.

Class Types :-

2+1 (two slots for download + 1 for upload)
3+1 (three slots for download + 1 for upload)
4+1 (four slots for download + 1 for upload)

GPRS is a mobile data upgrade to a GSM mobile phone network. This provides users with packet data services (similar to the Internet) using the GSM digital radio network. Each voice circuit in GSM transmits the speech on a secure 14kbps digital radio link between the mobile phone and a nearby GSM transceiver station.

The GPRS service joins together multiple speech channels to provide higher bandwidth data connections for GPRS data users. The radio bandwidth remains the same, it is just shared between the voice users and the data users. The network operator has the choice of prioritizing one or the other.

GPRS users will also benefit from being able to use GPRS while traveling as the GSM system should transparently hand over the GPRS connection from one base station to another.

GPRS Roaming - There are two type of GPRS Roaming

Home Network Roaming - Here all data is transmitted from wherever you connect to a GPRS network to your home GPRS network where it is connected to the Internet or your company LAN as if you were indeed in your home country.

Local Network Roaming - Data is just connected to a local Internet connection point and will be subject to local conditions for security and performance.

Radio Interface

Each GSM radio transceiver uses Time Division Multiplexing to deliver eight voice circuits on one radio channel. Each radio site may have one or more transceivers to provide sufficient channels to end users (maximum numbers are limited by many factors including - operators radio license, interference with other nearby GSM cells, cost of equipment, capacity of radio site infrastructure, etc.)

Each 14kbps channel may be shared by multiple 'connected' GPRS users (many users will be connected to the network but transmitting very little data). As a user's data requirements grow, they will use more of the available capacity within that timeslot, and then more available timeslots up to the maximum available or the maximum supported by their device.

In general the higher the data rate, the more power the mobile device will use and the shorter the battery life and the higher the transmitted RF power.

GPRS Tunneling Protocols will be updated soon….

Comments and Appreciations are most welcome.

ChEeEeEeErRrRrRs!!!

Telecom Tigers Team

telecomtigers@gmail.com

http://homepageforu.webs.com/

SIP (Session Initiation Protocol) Call Flow

2014-02-25T15:04:00.001+05:30

Hi All,

We have already discussed the basics of SIP in our last post. Here we would like to share the SIP call flow. Here we have also included PSTNs, so that the reader can co-relate the message of SIP and ISUP.

Scenario:

A Number wants to call B Number which is catered by PSTN B.

PSTN A to MSS X protocol used in ISUP.
MSS X to MSS Y protocol used in SIP.
MSS Y to PSTN B protocol is ISUP.

1) After receiving IAM from PSTN A with called party number as B number MSS X after number analysis detects the B number has to be routed to MSS Y which is connected by SIP. MSS X send a INVITE message.
Major components of INVITE are "Called Party", "Calling Party", "Bearer information", "Codec".

2) MSS Y receives INVITE and responds with 100 (Trying) message.
This response indicates that the request has been received by the next-hop server and that some unspecified action is being taken on behalf of this call (for example, a database is being consulted). At the same time after number analysis its send IAM to PSTN B.

3) MSS Y send 183 message to MSS X. This message is called as Session progress indicated that session is in progress. In response to 183 MSS A sends PRACK. PRACK (PRovisional ACKnowledgement) is like any another request within a dialog.
** PRACK is response for 1XX mesages
ACK is response for 2XX messages.

4) After analysis of B number PSTN B sends ACM with "Called Party status indicator = no indication" to MSS Y. MSS Y sends 200 message to MSS X in turn MSS X forwards ACM message to PSTN A.

5) When B number starts ringing PSTN B send CPG message with "Called Party status indicator = Subscriber free". Indicates that subscriber is free and ringing.
MSS Y send 180 ringing message to MSS X.

Which is communicated to PSTN A in CPG message and A number can hear a ringtone.

6) B number answers the call in response PSTN B send ANM message to MSS Y. MSS Y send 200(With ANM) message to MSS X. MSS X responds with ACK , also forwards ANM message to PSTN A. At this point of time speech path is through.

7) After conversation A number releases the call. REL is send from PSTN A to MSS X in response MSS X sends BYE message to MSS Y. MSS Y send the REL message to PSTN B.

8) PSTN B release the resources and respond with RLC message to MSS Y. MSS Y relays the 200(with RLC) message to MSS X. RLC is then forwarded to PSTN A. This complete the release of all resources used for call.

Comments and Appreciations are most welcome.

ChEEeeeEEeeeErs!!!
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

SIP Messages & Release Causes

2014-01-26T10:15:00.000+05:30

Hi All,
As we all know, now a days all the services in telecom are moving into IP domain, in which "Session Initiation Protocol (SIP)" plays a vital role, so here we go for SIP Call flow, but before that, we need some basics for the same,

SIP :- It's a text based protocol responsible for the establishment, management and tearing down of media sessions in an Internet Protocol (IP) environment.

SIP Messages :- It was designed using a request/response model, there are 2 types of SIP messages – request (method) and responses.

Request :- “A SIP message sent from a client to a server, for the purpose of invoking a particular operation. There are different requests – Invite, Register, Bye, ACK, Cancel and Options (Refer, Subscribe, Notify, Publish, Message Update, Info and PRACK)

Responses :- “A SIP message sent from a server to a client, to indicate the status of a request sent from the client to the server.” Responses are differentiated into 6 classes.

Response Class	Phase
1XX (Informational)	100 (Trying)
	180 (Ringing)
	181 (Call is being Forwarded)
	182 (Call Queued)
	183 (Session Progress)
2XX (Success)	200 (OK)
	202 (Accepted)
	204 (No Notification)
3XX (Redirection)	300 (Multiple Choices)
	301 (Moved Permanently)
	302 (Moved Temporarily)
	305 (Use Proxy)
	380 (Alternative Service)
4XX (Client Error)	400 (Bad Request)
	401 (Unauthorized)
	402 (Payment Required)
	403 (Forbidden)
	404 (Not Found)
	405 (Method Not Allowed)
	406 (Not Acceptable)
	407 (Proxy Authentication Required)
	408 (Request Timeout)
	409 (Conflict)
	410 (Gone)
	411 (Length Required)
	412 (Conditional Request Failed)
	413 (Request Entity Too Large)
	414 (Request-URI Too Long)
	415 (Unsupported Media Type)
	416 (Unsupported URI Scheme)
	417 (Unknown Resource Priority)
	420 (Bad Extension)
	421 (Extension Required)
	422 (Session Interval Too Short)
	423 (Interval Too Brief )
	428 (Use Identity Header )
	429 (Provide Referrer Identity)
	430 (Flow Failed)
	433 (Anonymity Disallowed)
	436 (Bad Identity-Info Header )
	437 (Unsupported Certificate)
	438 (Invalid Identity Header )
	439 (First Hop Lacks Outbound Support)
	440 (Max-Breadth Exceeded)
	470 (Consent Needed)
	480 (Temporarily Unavailable)
	481 (Dialog/Transaction Does Not Exist)
	482 (Loop Detected)
	483 (Too Many Hops)
	484 (Address Incomplete)
	485 (Ambiguous)
	486 (Busy Here)
	487 (Request Terminated)
	488 (Not Acceptable Here)
	489 (Bad Event)
	491 (Request Pending)
	493 (Request Undecipherable)
	494 (Security Agreement Required)
5XX (Server Error)	500 (Server Internal Error )
	501 (Not Implemented)
	502 (Bad Gateway)
	503 (Service Unavailable)
	504 (Gateway Timeout)
	505 (Version Not Supported)
	513 (Message Too Large)
	580 (Preconditions Failure)
6XX (Global Error)	600 (Busy Everywhere)
	603 (Decline)
	604 (Does Not Exist Anywhere)
	606 (Not Acceptable)

One of the most significant advantages of SIP trunking is its ability to combine data, voice and video in a single line, eliminating the need for separate physical media for each mode.

SIP call flow will be shared in coming month.

Till then happy reading, comments and appreciations are most welcome.

ChEEEEErs!!!
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

EXCEL Functions

2013-12-27T21:20:00.000+05:30

Hi All,

In any organization, to maintain a regular growth, we needs different Reports on Daily, Weekly , Monthly or Yearly basis, to check / compare / judge, the organization workings & to prepare / maintain those reports, Microsoft Office - Specially Excel is the best tool,

like In Telecom Domain, for KPI Improvement, Reports, we need lot of Excel.

So today, let’s discuss something about different Excel Functions, which enhance our ability to view, analyze & maintain the high performance of an organization.

Excel :- In Excel Everything is defined in ROW and COLUMN, & combination of both is termed as CELL.

In below image, (A,B,C,D,E) are Columns & (1,2,3,4,5,6) are Rows,

& B(Column) 2(Row) i.e. B2 (in which selected is written) are termed as CELL.

There are many different functions, which helps to work with Excel really very easy & normally function in Excel starts with “=” (equalto) Sign,

So lets start with some functions,

Excel Functions :-

Mathematics -

SUM :- Its used to ADD its arguments (values).
AVERAGE :- Its used to AVERAGE its arguments (values).
MIN (Minimum Value) :- Its used to get MINIMUM Value from given Values.
MAX (Maximum Value) :- Its used to get MAXIMUM Value from given Values.
COUNT :- Its used to get Total Count of given Values.
PRODUCT :- Returns Product of given Values.
POWER :- Returns POWER of given Value.

Database -

LEFT: - Returns the leftmost characters from a Text Value.
RIGHT: - Returns the Rightmost characters from a Text Value.
MID: - Returns the specific number of characters from a text string.
CONCATENATE: - Joins several text items into one text item.
LOWER: - Converts text to lower-case.
UPPER: - Converts text to upper-case.
PROPER: - Capitalizes the first letter in each word of a text value

Date -

TODAY: - Returns the Current Day Date, “=TODAY()” (formula without Inverted Commas).
NOW: - Returns the Current Date & Time, “=NOW()”.

Vlookup :- This function helps to find out the specific item in the given database.

“=VLOOKUP(ItemToFind,RangeToLookIn,ColumnToPickFrom,SortedOrUnsorted)”

ItemToFind – finds the single item, as required, like A11 or A12 or A13 (below Image)
RangeToLookIn – it’s the range of data i.e Database, in which data needs to be found, like in below image - Database is from (A1 to D8).
ColumnToPickFrom – how far is the column from the LEFT MOST Column.
SortedOrUnsorted – Whether Columns headings are sorted, TRUE(1) for YES, FLASE(0) for NO.

Note in Vlookup – Item to be found from the given database, that item column should be LEFT MOST Column in Database.

As in below image, the database is from (A1 to D8), & we need to find the Person Values, which is in A11, A12 & A13, hence in database, the Person Column is the Left Most Column i.e. Column number 1.

Hlookup :- Its same as Vlookup, but in this ROW-wise data selection is there & that row should be TOP MOST in entire database.

These above are the few Functions in Excel, there are lot more like Charts, Pivot Tables, etc. which makes working with Excel a real FUN...

Comments are most Welcomed.

ChEEEEERrrrrRssSS...
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

PostPaid Call Flow

2013-11-07T11:53:00.004+05:30

Hi All,

Many of our blog readers are asking for Postpaid Call Flow, So here's it goes,

Here we tried to explain very basic call flow from mobile to mobile.

To make it simple following assumptions have been taken. A) Call is in same MSC and BSC. B) No Authentication, C)No Ciphering , D) Messages on Ater and Air interface are not consider, etc.

Call Flow Message Details:-

CM Service Request – Message contains Global Cell Identity, Kind of Service required by subscriber e.g Voice, SMS, Fax, USSD. Mobile Identity e.g TMSI/IMSI.
CM Service Accept – Message is in response of CM Service Request.
Set Up - Message contains dialed number from Mobile A (i.e Mob B number) and speech Codec.
Send Routing Info-Request (SRI) - After analysis of dialed numbers received from A in set up message, MSC recognizes its own MSISDN series and send SRI to HLR to get the Mobile station roaming number(MSRN). This messge contains B MSISDN, Interrogation type e.g Basic Call etc.
Assignment Request - Message is to seize a channel for voice call for Mob A between MSC and BSC. Message contains Circuit Identification Code(CIC).
Assignment Complete - Acceptance from BSC end that same CIC has been seized.
Provide Roaming Number Request - HLR checks in its database to which VLR, Mob B is registered & ask for roaming number from that VLR. Message contains IMSI, MSISDN, VLR ID of Mob B.
Provide Roaming Number Response - Message is response of roaming no. request and contains roaming number of Mob B. This message is for HLR. In this VLR checks its database & allocate one free MSRN from its MSRN pool for B number.
Send Routing Info-Response - In this HLR forward same roaming number which it receives in above message to MSC.
Paging Request - In this VLR checks the MSRN received from HLR & search which MSISDN is against that MSRN, now MSC checks the VLR database of that MSISDN to get the LAC & TMSI/IMSI of that MSISDN (Mob B) & initiates the paging request message to that particular LAC on the basis of TMSI/IMSI in that BSC. BSC now page to that LAC on the basis of IMSI/TMSI of Mob B. Message contains LAC, IMSI/TMSI, DPC of BSC.
Paging Response - Mob B response to that paging with GCI (Global Cell Identity) to BSC that intern forwarded to MSC.
Assignment Request - Message is to seize a channel for voice call for Mob B between MSC and BSC. Message contains Circuit Identification Code(CIC).
Assignment Complete - Acceptance from BSC end that same CIC has been seized.
Set Up - It is used to display Mob A number on Mob B handset.
Alert - This message indicates Mob A that Mob B is connected & its ringing. The Ring Back Tone is send from MSC to Mob A.
Connect - Mob B answers the call & connect message from Mob B is send to MSC, intern MSC sends connect message to Mob A indicating that phone has been answered & connects those 2 voice channels which were seized during the assignment complete message.
Connect Acknowledge - To acknowledge the connection.

Comments are most Welcomed.

CheeeeRRRRssss...
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

Blog Readers - Questions & Answers

2013-10-09T17:18:00.002+05:30

Hi All,
Many of our blog readers used to ask different question in Telecom Domain & We happily Answer them, & those answers only reached to those who raise the question, but,
Today, I'm updating Some of those questions & answers, so that everyone can clear their doubts (if they have), regarding those topics, & also anybody can mail us (telecomtigers@gmail.com) there question & we'll try to answer them, to clear his/her doubts in telecom domain.

Thanks, all blog readers for their Positive Response.

Question from Piyush Kumar,
Hi,
Can u please tell me in details about the call flow when both the subscribers are roaming in different PLMN & both belong to same PLMN HLR..

Answer by TT Team,
We believe you are asking about call flow where Subscriber A is calling Subscriber B and both belong to same PLMN (Z) and roaming in different PLMNs (Sub A in PLMN X and Sub B in PLMN B)

I ll try and cover only important steps as basic call flows are covered in blog.
1) Subscriber A calls subscriber B.
2) PLMN X MSS send SRI to MNPDB and find subcriber B is of PLMN Z
3) LRN for PLMN Z is added to B number and routed to NLD towards PLMN Z
4) PLMN Z analyzses LRN, Sees its own LRN send B number for SRI query toward HLR
5) HLR find that subscriber B is roaming in PLMN Y and send SRI to PLMN Y MSS
6) PLMN Y MSS in response send MSRN in response
7) After receving MSRN PLMN Z routes the call on MSRN to NLD.
8) After receving MSRN in PLMN Y pages the subcriber B and completes the call
Hope we are able to explain. In case of any query pls revert.
Question from Piyush Kumar Continued ---
Thanks a lot for the reply. The scenario is clear. Just wanted to know that the voice path established will be from X to Z then to Y or direct from X to Y.
Answer by TT Team - Voice path from X-->Z-->Y

Question from Yahya Al-Kharabhsheh eng_yahya
Dear Sir,
I would like to thank you for the subject that you posted on your blog about Normal Prepaid in call flow
and I would be grateful if you help me to send me another scenario for the same subject prepaid call flow but using roaming on the same network but on another country
thank you
Eng.Yahya KH
Computer Engineer

Answer by TT Team,
Hi,
There not much difference in prepaid roaming MO call flow only thing one has to remember that always home IN/SCP will be queried. So just assume that IN/SCP is home IN /SCP and rest remains same.
Normal Prepaid (IN) Call Flow
Pleas note MT on prepaid roaming subscriber is interesting and different than normal perpaid MT call flow.

Thanks
Telecomtigers

Question from muhammad sajid bashir
A.O.A
i am sajid Bashir from Multan City...i like your info at page.. v informative and interesting data..which is put by you..i hope u ll update my info about telecom.
Best Wishes for you.

Answer by TT Team,
Hi Sajid,
Good to see that you appreciate our blog. Thanks.
We will certainly try and help you regarding telecom knowledge. Just keep reading our blogs and feel free to raise question/query in blog.

Thanks
Telecomtigers

Question from Abdullah Iqbal
Dear Telecomtigers team Hello,
at first appreciate you and thanks for your kind collaboration, following the issue that we discussed before related to Final Project about the title of" On Net Mobile To Mobile Call Flow in GSM system" I should research and calculate materials for completing the project and defense then in the final for completing my Credit so kindly request of you have any concept or any same PDF chapter or any upgraded it to you blog then let me to know, if you can then I'm looking forward to send me as soon i will appreciate as the most!
for any kind of question let me to know.

Thanks & Rgs,
Abdullah Iqbal
ICT- January Student

Answer by TT Team,
Hi Abdullah,
" On Net Mobile To Mobile Call Flow in GSM system" On Net means call within same network. Off Net means means calling from one operator to other opertaor. (GSM) Mobile to Mobile Call Flow, Within Same MSC/BSC Will be ON NET call. You can use the same in your project.

Regards
Telecomtigers

Question from Ankit Mishra, kalpithakudipady, amrendra12, umakant.1.hale, imrahultiwari, arunntwk, saiviky, nandadeb.mail, r.goyal1984,
Hi Sir,
Your blog is wonderfull,I gained so many knowledge for telecom about various terms and call flows.
Kindly share the numbers and mail address of telecom consultants as you have mentioned in your blog.
Will be thankful to you.

Answer by TT Team,
Hi,
Find the attached Consultants List,
Start forwarding your CV & i hope u'll get, job of your choice soon,
Best of Luck !!!

Question Abdullah Iqbal
Hello Dear Sir/Madam
it was so interesting issue below of GSM mobile to mobile call flow-within same MSC/BSC. As i interested to prepare a Final Project for gradaduation of university i will choose the above title to defence it and doing research about the issue, but need for you collaboration that how should i find more materails.

Need for yourfeedback
thanks

Answer by TT Team,
Hi Abdullah,
Thanks for appreciating the blog!!!
Good to know that you are interested in making project on GSM call flow. This call flow contains various network elements involved in it exp. MSC,BSC,BTS,HLR Kindly specify in which domain you require help. We will try and help.

Thanks
Telecomtigers Team

Question from inderjeet singh
Hi, it would be great favor if somebody emphasizes more on CCR. like in our switch the CCR value is is between 60%-90% which we wants to maintain at >=90% all the time. SO being a switch guy what all the steps i should take to improve this figure at 90% and above.

Answer by TT Team,
Hi Inderjeet,
CCR is Call Completion Rate & its totally depends on one of the ISUP messages i.e. ACM messages,
%CCR = (ACM / IAM) * 100
Good value for the same is > 98%,

To Improve following steps can be taken :-
1. Check for announcement mapping i.e. check for every release cause whether announcement mapping is there or not & proper announcement mapping should be there.
Specially check for announcement mapping in case of Roaming Subscribers.
2. If possible activate Early-ACM or Pre-ACM.
3. Check for cases in trace in which ACM not receiving, generally for User Busy case, directly REL (User Busy) is send after IAM, avoiding ACM message, to save some resources.

Regards
TT Team
http://homepageforu.webs.com/

Question from Abhinandan
Hello Tigers,
Myself Abhinandan, it has been some days since im following ur blogs and got some knowledge also thank u for that. Guys i need a help from you currently im working as a tech support network engg at an isp Youbroadband im trying to change my job one of my friend works at Sasken network engg, says his company is hiring now n i wanna give interview der but the problem is openings are with the Telecommumication end and im with the router's gateway's ip networking. Growth is good with Sasken n i ve to clear the interview with telecommunication also like gsm call flow's etc etc can u help me out with basic telicommunication and normally wat type of interview questions asked with telecom industry.

Waiting for your replay and suggestions,

Thanks and regards
Abhinandan.k

Answer by TT Team,
Hi Abhinandan,
Its really nice to hear, that u got a call from a good company (Sasken),
Regarding interview, generally questions about Call Flows, Signaling, Sigtran, Routing, MNP, etc. can be asked, for the same, u can refer the Blog different section, like "Call Flow", "Signaling", "Interview Q-A", Telecom Terms, MNP, etc.

All the Best
Regards
TT Team

Question from rajesh Kumar
Dear Team,
Pl provide Interview Q&A for O&M profile - Switch
1. Call Flow - between same MSC's, or When Subscriber is on Roaming ?
Q2. Call Forward Concept ?
Q3. Call Flow Through Channels, Details ?
Q4. About KPI reports, CGR Reports ?
Q5 What is Erlang and how to improve ASR ?
Q6.what is max. link load?

Regards
Rajesh kumar

Answer by TT Team,
Dear Rajesh,
Please go through the Blog, we believe most of your queries will answered there.
If not please write in to us.

HaPPy Reading
ChEEEEERs!!!!
Telecomtigers

Question from nagendra B & Anshul
hi tigers...
i saw ur blog recently & i thought y i missed such a gud blog from so many days..
so coming to query,, i am confused with roaming call flows for sms & gsm call flow..
i have a great problem with gmsc ..where it comes into picture..lyk those..
so plz do share me .. plz..

thanks in advance...
--- B nAgEnDrA bAbU ---

Answer by TT Team,
Hi Nagendra,
Will consider that Aircel Mumbai (A) and Tata Kolkatta (B) are roaming in Vodafone Delhi.
And A is sending SMS to B.
To make it less complicated the flow changes due MNP are not included :)

When A send a SMS to B.
1) MO_forward_SM from Vodafone MSC will be send to SMSC which is stored in handset as SMSC centre in this case
it will Aircel MUmbai SMSC.
This will done by GT routing wherein Vodafone delhi must have routed the GT of Aircel Mumbai to STP.
MO_forward_SM will go directly to Aircel SMSC or via Aircel Mumbai GMSC that depends on the connectivity and routing.

Typical flow
Vodafone Delhi MSC--> Voda Delhi STP-->Voda Mumbai STP--> Aircel GMSC/STP--->Aircel SMSC

2) Forward_SM_response from Aircel Mumbai SMSC will follow the path back to Vodafone Delhi MSC.
That again depends on routing from SMSC whether via STP or via Aircel Mumbai GMSC through STP.
Once sucessful Forward_SM_resp is recived message is delivered sucessfully to SMSC and handset shows
"Message sent" display.

In short and MO SMS leg is completed.

We will discuss the MT part now message has to be delivered to Tata kolkatta number which is roming in Vodafone Delhi.

3) Aircel Mumbai after looking at B number series initaites the SRI_SM (Send Routing info for Short message)
towards TATA Kolkatta HLR.
This message to get the current VLR where the B number is situated.Flow agin depends on routing

Typical flow
Aircel SMSC--> Aircel Mum GMSC/STP--> Aircel KolKatta GMSC/STP--> Tata Kol STP/GMSC--> Tata Kol HLR

4) Tata HLR will check the curent VLR of subscriber and return in SRI_SM_Resp
Ideal flow will be same as above in reverse manner.

5) After getting VLR address in SRI_SM_Resp now Aircel SMSC knows the correct adddres where SMS has to be delivered.
SMSC send MT_Forward_SM to Vodafone Delhi VLR(MSC) where the subscriber is currently registered.
Typical flow will be same as in Step 1 but in reverse order.

6) Vodafone MSC acknowledge SMSC by MT-FSM response which contains status of MT SMS.
i.e delivered or failed cause if SMS is not delivered to B number.
Flow remians same as in Step 1

Typical flow can change accroding to routing and are operator planning dependent. But Mssages exchange between different nodes (Marked in Bold) are standard and remains same.

Hope we helped in clearing your doubt in case of any mystery still remains unsolved feel free to revert.
Also go through the MNP SMS call flow.

MNP SMS Flow

ChEEEErS!!!!

Keep checking for new posts till than HaPyYyYy Reading.

Comments are most Welcomed.

ChEeEeEeRrRrRrRrs..
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

LTE Network Architecture

2013-09-04T15:12:00.001+05:30

Hi All,

Lets today discuss something more about LTE i.e. its Architecture.
It mainly consists of 3 Main Components :-

Evolved Packet Core (EPC).
User Equipment (UE)
E-UTRAN - Evolved UMTS Terrestial Radio Access Network.

Evolved Packet Core :-

Its an IP-Based core network system. Its a Always-On Connection. All Services including Voice calls are carried by IP Network i.e. VOIP (Voice Over Internet Protocol).
Components of EPC are - MME, S-GW, P-GW, HSS, PCRF, etc.

MME (Mobile Management Entity) - Responsible for Establishment & Releasing of Signaling (bearer) between User & Packet Core Network. Handles Mobility Management like Location Registration, Authentication, Handover with HSS (Home Subscriber Server).
S-GW (Serving Gateway) - It acts as Router, forward & receive data between Wireless Base Station eNodeb or 3GPP access networks such as 2G/3G & the PDN (Packet Data Network) Gateways (P-GW). for Roaming, S-GW & P-GW provides boundaries between Operators.
P-GW (Packet Data Network - PDN Gateway) - It Communicates with outside world using SGi interface. Each PDN is identified by an Access Point Name (APN). Its functions includes IP Address Assignment to Terminals, User Authentication, QoS (Quality of Service) Control, Charging Data (as per PCRF), also capable of Deep Packet Inspection (DPI) - Involves either to Pass or Drop the User Data Packet.
HSS (Home Subscriber Server) - Its like HLR (Home Location Register), Its a Central Database, contains all information about all network operator's subscriber.
PCRF (Policy Control & Charging Rule Function) - Its responsible for Policy Control Decision Making. It function is to either accept or reject data packets & also check the charging method from users & instruct S/P-GW & Access Network to work accordingly.

User Equipment (UE) :-

Its same as the mobile equipment used in UMTS & GSM Network. It contains following modules like,
ME (Mobile Equipment) - handles all Communication Functions.
TE (Terminal Equipment) - Terminates the Data Stream.
UICC (Universal Integrated Circuit Card) - Also know as SIM Card, which stores user specific data, like home network identity, security keys, user's phone number.

E-UTRAN (the Access Network):-

It handles all the Radio Communications between Mobile & EPC, It provides Higher Data Rates, Lower Latency & Specifically designed for Packet Data. It has just one component i.e. Evolved Base Station called eNodeB or eNB, which interfaces with UE.
Each eNB is a Base Station that controls mobiles in one or more cells. The Base Station that is Communicating with a Mobile is term as Serving eNB.
eNB connects with each other via X2 Interface & they connect to the PS core network via S1 Interface.

More Updates Coming Soon, till than HaPpPpPpYyYyYyYy Reading.

Comments are most Welcomed.

CheeeeEEEERs..
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

LTE - Long Term Evolution

2013-08-02T14:47:00.000+05:30

Hi All,

Today, Lets discuss something about the Latest Technology, LTE (Long Term Evolution),

Its a standard for Wireless Communication of High-Speed Data for Mobile Phones and Data Terminals.

The Increase in Usage of Mobile Data Transmission & New Mobile Application such as MMOG (Multi-Media Online Gaming), Mobile TV, Web 2.0, Streaming Contents, Voice-Over-IP (VOIP), have Motivated the 3rd Generation Partnership Project (3GPP) to work on LTE.

The Goal of LTE was to Increase the Capacity & Speed of Wireless Data Networks, Provide Low Latency (delay), Packet Optimized Radio-Access Technology, Supports Flexible Bandwidth using new Digital Signal Processing Techniques and Modulations.

It Supports Scalable Carrier Bandwidths, from 1.4 MHz to 20 MHz and,
Supports both Frequency Division Duplexing (FDD) & Time-Division Duplexing (TDD).

In FDD, Uplink & Downlink Transmission used Different Frequency, while

In TDD, Uplink & Downlink use the Same Carrier (Frequency) & are Separated in Time.

It Redesign & Simplifies the Network Architecture to an IP-based System with significantly reduced Data Transfer Latency.

Its Specification Provides Downlink Peak Rates of 300 Mbit/s, Uplink Peak Rates of 75 Mbit/s.

Advantage :-

High Throughput - High Data Rate Transfer can be achieved in both Uplink & Downlink Transmission.
Low Latency - Time required to connect to the Network is very less i.e. is in range of few Hundred Milliseconds.
Improvement in User Experience - Optimized Signaling for Connection Establishment, Other Air Interface & Mobility Management.
Simple Architecture - All Interface between Nodes are IP-based, which Reduces the Operating Cost, & Provides Easy Maintenance.

QoS (Quality of Service) - It supports Hard QoS, with end-to-end quality of service and Guaranteed Bit Rate (GBR) for Radio Bearers.
Various levels of QoS can be applied to LTE traffic for different applications.

More Updates will be Updated Soon, till than HaPpPpPYyyyy Reading.

Comments are most Welcomed.

ChEeEeEeEeRs..
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

Network Topologies

2013-04-19T17:58:00.001+05:30

Hi All,

Let's discuss today, about Network Topologies i.e. how devices within network are connected & how they can communicate with each other,

There are basically 2 ways to define network topologies:-

1 Physical Topology – This defines Actual Layout of Wires or Media.

2 Logical Topology – It define, how Media is accessed by Host for Transmitting

Below are the Different Topologies, by which Network can be Connected :

Bus Topology – This is the Simplest one i.e. In this, there is Single Backbone Cable which terminates at both end & all devices (computers, printers, laptops, etc.) are connected to this Cable.
Advantage – 1) Easy to Connect any Device 2) Comparatively requires Less Cable Length.
Disadvantage – 1) If Backbone cable Breaks, Entire Network Shut Down 2) Termination required at both end 3) Difficult to diagnose the Fault.

· Ring Topology – In this each computer are connected to its previous & next computer, to form a path for data transmission like a Ring.

Advantage – 1) Organized 2) It doesn’t requires any Network Server for data transmission 3) Easy to identify the issue, when whole network goes down 4) chances of Collision are very Less.

Disadvantage – 1) Only 1 machine can transfer at a time 2) Each Data Packet must pass through each computer, whether they require or not, which makes it slow w.r.t. Star Topology 3) If 1 Machine fails, whole network is Down.

Star Topology – As the name implies, it resembles STAR, in this each machine is connected to a central HUB & each machine has to pass through this HUB for data transmission among them. The HUB acts as Signal Booster or Repeater.

Advantage – 1) Easy to Install & Configure 2) Easy to Add or Remove Devices 3) Doesn’t impacts network, if any link goes down.

Disadvantage – 1) if HUB fails, whole network goes down 2) More expansive & more cable required than Bus Topology.

Mesh Topology – This Provides maximum protection from Service Interruption, as in this, all machines are connected to each other which provides multiple routes to each machine.

Advantage – 1) Maximum Protection 2) Able to transmit data from one node to multiple node at a time 3) If 1 nodes fails, than there are alternate path for data transfer 4) Expansion or removal of nodes can be easily done, without disrupting other nodes. 5) Point-to-point link make fault identification and fault isolation easy.

Disadvantage – 1) Costly 2) Redundant paths, which may be of no use, from each node. 3) Network is Very Complex, hence maintenance is very tough.

Tree Topology – It’s a Hybrid Topology i.e. Combination of Star & Bus Topologies, in which group of nodes are connected like in STAR topology & than many Stars-Connected Network are connected to each other via Main Bus.

Advantage – 1) Good Choice for Large Networks 2) Expansion & Management of Network is Easy 3) If one Segment is down, it doesn’t affect others.

Disadvantage – 1) If Central Bus goes down, whole network breaks. 2) Maintenance becomes difficult as the Network Grows.

Keep checking for new posts till than HaPyYyYy Reading.

Comments are most Welcomed.

ChEeeeeeRs..
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

Networking Devices

2013-03-12T17:09:00.002+05:30

Hi All,

Today let’s discuss something about different devices used in Networking Domain.

These are used to connect different devices like computers, printers, scanners, etc. to a network, so that they can communicate easily.

These devices are – NIC Card or LAN Card, Repeaters, Hubs, Bridges, Switches, Routers.

NIC Card (Network Interface Card) – It’s a PCB (Printed Circuit Board) Card in a Computer, & provides communication within locally connected devices. It has 48 bit serial number called MAC (Media Access Control) address. It’s a Layer-1 (Physical) & Layer-2 (Data Link Layer) device.

Repeaters – It’s a device used to Re-Generate the Signals. It regenerates electrical, wireless & optical signals. It helps to transmit signals to a longer distance, which becomes week due to transmission loss.

Hubs – These devices are used to connect different devices like computers, printers, etc. to a common LAN (Local Area Network), which helps to share resources. It’s like a Junction box, where LAN cables from different computers connects & allows computers to see network as a Single Unit. It’s a most commonly used device within house networks since it offers inexpensive option.

Bridges / Switches – As the name implies, it provides communication between different LAN’s using same protocols like Ethernet. It’s a Layer-2 (Data Link Layer) device. In this, message is forwarded to every device using MAC address within network & only specific device (for whom message is addressed) responds. These devices are generally used within small networks since it broadcasts every message to each possible destination which would generate unnecessary traffic.

Difference Between Bridge & Switches–

Switch operates with Higher Speed than Bridge.
Normally Switch has more ports than Bridge.
Switch can operate in both (Half & full Duplex) mode, while Bridges only operates in Half-Duplex mode.
Packet forwarding in Switches are hardware based, while in Bridge its Software based.

Routers – It’s a Layer – 3 (Network Layer) Device & filter data based on IP address. It helps in determining optimal path for transmitting data from network to another network. It’s used to connect different LANs or a LAN with a WAN (e.g. the internet). It can regenerate signals, concentrate multiple connections, convert data transmission formats, and manage data transfers. It helps in controlling both Broadcast & Collision Domain.

Keep checking for new posts till than HaaaPPy Reading.

Comments are most Welcomed.

ChEeEeEeRs..
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

OSI Reference Model

2012-12-19T12:59:00.000+05:30

Hi All,

Today let discuss something about OSI (Open System Interconnection) Model, which was created by ISO (International Organization for Standardization), So that different manufacturer computers can communicate with each other by connecting them within network.

OSI Reference Model :-

The OSI Model has 7 different layers, divided into 2 groups. The top 3 layers define how the applications within the end stations will communicate with each other & with users. The bottom 4 layers define how data is transmitted end to end,

1. Application Layer: - It helps users to communicate with the computer. This layer comes into picture when it finds that user going to access the network soon. This layer acts as an interface between actual application program (which isn't at all part of layered structure, e.g. Internet Explorer (IE), Firefox, Google Chrome, Microsoft Office, etc.) & next layer down (i.e. Presentation layer) by providing ways for the application to send information down through the protocol stack. It’s also responsible for determining whether sufficient resources for the intended communication exist. Some programs which actually reside at this layer are FTP, TFTP, etc.

2. Presentation Layer: - This layer is a translator i.e. it presents data to the application layer & is responsible for data translation & code formatting. It adapts the data into standard format which helps in successful data transmission, various tasks like data compression, decompression, encryption & decryption comes under this.

3. Session Layer: - This is responsible for Setting up, Managing, & then Tearing down the sessions between Presentation layer entities. It’s also provides dialog control between devices & nodes. It offers three different modes of communication: Simplex, Half Duplex, & Full Duplex. This layer basically keeps different application data separate from other application data.

4. Transport Layer: - It provides end-to-end data transport service by establishing a logical connection between sending & receiving host on inter-network This layer segments & reassembles data (from upper layers) into the same data stream. TCP (Transmission Control Protocol) & UDP (User Datagram Protocol) works at Transport Layer. This layer is responsible for providing mechanism for multiplexing upper layer applications, establishing sessions, & tearing down virtual circuits. It also hides details of any network dependent information from higher layers. This layer can be Connection-less or Connection-Oriented (Reliable Data Transfer).

5. Network Layer: - It manages the network addressing. It tracks the location of the devices on the network & figure out the best way to route data packets. Device used in this layer are Routers & in Packet form data transmission occurs. 2 types of Packets are used – Data Packet & Route Update Packet.

Data Packet – It’s used to transport User Data & protocols used to support data traffic are called Routed Protocols, for e.g. IPv4, IPv6.

Route Update Packet – Used to update neighboring routers about the network connected. Protocols which send route update packets are called Routing Protocols, for e.g. RIP, RIPv2, EIGRP & OSPF. It helps to maintain routing tables on each router.

6. Data Link Layer: - It’s a Hardware based Switching, It provides the physical transmission of the data & handles error notification (not correction), network topology, & flow control. It ensures that message delivered to the proper device on a LAN using Hardware address & translate message from network layers to Bits for Physical layer to transmit. It has 2 sub-layers,

Media Access Control (MAC) 802.3 – It defines how packets are placed on the media. Error notification (not correction), ordered delivery of frames & optional flow control can also be used.

Logical Link Control (LLC) 802.2 – In this, a host will receive the frame & looks in the LLC header, to find out the destination of the packet i.e. it is responsible for identifying Network layer protocols & then encapsulates them. It also provides flow control & sequencing of control bits. Switches & Bridges are used in this layer & uses Hardware (MAC) address to filter the network.

7. Physical Layer: - It specifies the electrical, mechanical, procedural, & functional requirement for Activating, Maintaining, & Deactivating a physical link between end systems. Hubs & Ethernet are used in this layer.

Below is the Summary of all OSI Layers Functioning,

Keep checking for new posts till than HaPPy Reading.

Comments are most Welcomed.

ChEeEeEeEeEeRrRs
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

What is IP (Internet Protocol)

2012-11-23T18:20:00.001+05:30

Hi All,

Greetings,

In today’s scenario major part of telecom is shifted towards Data (IP Backbone) which helps, to reduce the cost, enhance the performance/efficiency of the network, hence we are shifting TDM based system towards IP Based,

So let’s just know something about IP addresses.

What’s IP (Internet Protocol) Address:-

It’s a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication.

It’s a 32-bit number, It is represented in dot-decimal notation, which consists of 4 decimal numbers, each ranging from 0 to 255, separated by dots, e.g., 127.0.0.1 (Loop Back Address).

Each part represents a group of 8 bits (octet) of the address.

It serves 2 Principal Functions :-

Identifies the system's network address &
Identifies which particular machine it is on the network, The Host part.

IP addresses are divided into 5 classes -

Class A addresses are assigned to larger networks,

Class B addresses are used for medium-sized network,

Class C for small networks,

Class D for Multicasting,

Class E for Research Organizations – Experimental Purposes.

Details :-

Ranges 127.x.x.x are reserved for the loopback or diagnostic functions, e.g, 127.0.0.1 is the common loopback address.
Range 255.255.255.255 broadcasts to all hosts on the local network.

Note :- Till now we are using IP address as IPv4 (32 Bits) but due to enormous growth of Internet & decreasing amount of available addresses, a new version of IP address is developed i.e. IPv6, which is 128 Bits & its implementation is ongoing.

The preferred IPv6 address representation is: xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx where each x is a hexadecimal digit (0-9, A-F) representing 4 bits, This notation is commonly called string notation.

More information, updated soooonnnnn...

Keep checking for new posts till then HaPPy Reading.

Comments are most Welcomed.

ChEEEEEERrRs
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

Normal Prepaid (IN) Call Flow

2012-04-14T00:45:00.000+05:30

Hi All,

As Prepaid Call Flow with MNP is already posted, but still many of our friends ask us for detailed Normal Prepaid (IN) Call scenario, so here you go,

The above flow describes a basic direct dial call scenario with normal call termination:

1. Mobile A starts a new call by dialing Mobile B.

2. The MSC sends an IDP (Initial Detection Point) event, which notifies the IN-SCP of the new call.

IDP Message Contains :- A-Party no, B-Party no., Service key=90, A Party Location, Time stamp.

3. The IN SCP processes the request and after authorizing the user, the IN SCP sends 3 IN messages to the MSC -

AC (Apply Charging) :- Check the A-Party Balance / tariff related facilities & provides maximum granted time for a call.
CIQ (Call Information Query) :- IN request from the MSC for call information, like CAET - Call Attempt Elapsed Time (time between call ringing & user picks the call), CCET - Call Connect Elapsed Time (Duration of a call), CST - Call Stop Time (exact time when call disconnect), RC - Release Cause (Exact release cause due to which call got disconnected).
RRBCSM (Request Report Basic Call State Module) :- IN again request from MSC for detailed Release Cause.

4. Connect :- After getting everything OK i.e. all request from IN side have been done then IN sends a Connect message to MSC for further call processing & connect the call.

5. Activity Test :- After IN provides "connect" message to MSC, its a sort of ping message which is unidirectional, sent by IN to MSC, to know the progress of a call.

6. Once the connection is made, an event report (for answer event) is sent to SDP via IN-SCP.for preventing any revenue loss.

7. After conversation, when call gets disconnected, a new event report is sent to SDP via IN-SCP, which in turn instructs to release the call.

8. Once the call is released, a new Apply Charging Report (ACR) is sent to IN-SCP, which contains full time usage data of a call. This report is sent to SDP for accurate & final call charging.

9. CIR (Call Information Report) :- By using the details which was noted in CIQ message, MSC makes a report i.e. CIR (which contains CAET, CCET, CST, RC) & sends to SDP via IN-SCP.

10. ERB (Evert Report BCSM) :- Another report send by MSC to IN, which contains actual release cause in details, which may be - Abandon, B-Party Busy, B-Party no answer, B-Party not reachable, route selection failure, disconnect.

11. Finally signaling terminates, which ends the call.

Keep checking for new posts till then HaPPy Reading.

Comments are most Welcomed.

ChEeEeEeRrRrRs
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

USSD Workflow & Benefits

2011-11-25T13:07:00.001+05:30

Hi Friends,

Here are some more details about USSD Workflow & Benefits,

Working Principle:-

USSD Originated at Network Side

USSD Originated by HLR – In HLR, application is there from where it originates a session with MSC/VLR, sends a USSD_REQUEST or USSD_NOTIFY messages to MSC/VLR & waits for the response. As the response received by MSC/VLR, HLR releases the session or sends another USSD_REQUEST or USSD_NOTIFY messages on the same session. After receiving the USSD messages from the HLR, if the MS is reachable, the MSC/VLR originates a session to the MS and transparently transmits the received USSD messages and the subsequent messages between the MS and HLR. If one of the sessions (the session between the HLR and MSC/VLR and that between the MSC/VLR and MS) is released, the MSC/VLR releases another session.
USSD Originated by MSC/VLR - In MSC/VLR, application is there from where it originates USSD_REQUEST or USSD_NOTIFY messages, if the MS is reachable, the MSC/VLR originates a session to the MS, sends an USSD_REQUEST or USSD_NOTIFY message to the MS, and then waits for the response. MSC/VLR controls the session. After receiving the response from the MS, the MSC/VLR can release the session or sends another USSD_REQUEST or USSD_NOTIFY message on the same session. In certain cases, such as application timeout in the MSC/VLR, the MSC/VLR can release the session before receiving the response from the MS.
USSD Originated by External Nodes - The external nodes, such as the USSD center and SCP (Service Control Point/IN), can originate USSD, Based on the routing mode of the short message center in sending short messages, the external node sends a message to the home HLR of the subscriber. If the MS is reachable, the HLR sends the address of the MSC/VLR that serves the MS to the external node. After obtaining the address, the external node directly sends an USSD_REQUEST or USSD_NOTIFY message to the MSC/VLR. The MSC/VLR then transparently transmits the message to the MS. The subsequent messages between the external node and the MS are also transparently transmitted by the MSC/VLR.
Processing of MS for USSD Operation Originated by Network - The MS may receive, at any time, the USSD operation originated by the network. If the MS has an on-going USSD operation or a supplementary service that is unrelated with calls, the MS rejects the USSD operation originated by the network. If the MMI (Man-Machine Interface) does not meet the requirement of USSD, the MS also rejects the USSD operation originated by the network. If the MS does not support the characters of the USSD operation, the MS sends a message to inform the network.

USSD Originated by MS (Mobile Station)

Processing of MS – Before originating USSD, the MS sets up the CM connection with the network. After the CM connection is set up, the MS sends the USSD request to the MSC and waits for the response. After receiving the response from the network, the MS displays the received information for the subscriber. When the MS waits for the response, the MS may receive a USSD_REQUEST or USSD_NOTIFY message sent by the network. Upon receiving the message, the MS processes accordingly and then continues to wait for the response to the initial USSD request.
Processing of MSC/VLR - After receiving the USSD message sent by the MS, the MSC/VLR processes the message based on the SC (Service Code) in the message. Depending on SC, MSC/VLR processes the USSD operation in the local office or with HLR, if the MSC/VLR does not support the characters in the USSD message or if the session cannot be set-up with HLR, the MSC/VLR returns an error to the MS.
Processing of HLR - After receiving the USSD message, the HLR processes the message. If the HLR does not support the characters in the USSD message, the HLR informs the MS and releases the session.

USSD Benefits:-

For Carriers - Many Real-Time value-added services can be provided, such as those providing stock, lottery, weather forecast, and airline information. These services can attract subscribers.
For Mobile Subscribers - Subscribers' requirements in many fields can be fulfilled, such as querying lottery information and stock information.
Applicable-to Network – It’s applicable to all the GSM/UMTS networks, There is no special requirement for software/hardware, but USSD center is required.

Flow details will be coming soooon...

Keep checking for new posts till then HaPPy Reading.

ChEEeeerS

Telecom Tigers Team

telecomtigers@gmail.com
http://homepageforu.webs.com/

Difference between USSD & SMS Messages

2011-09-20T11:31:00.002+05:30

Hi All,

Greetings from TT Team,

SMS & USSD both are GSM Services, On one hand both appear similar technically and functionally, but there are considerable and significant differences in their technologies and features.

The basic difference between the two technologies is,

USSD (Unstructured Supplementary Service Data) is session-based,
SMS (Short Message Service) uses the store-and-forward approach.

Below are some more differences :-

Message Flow details will be coming soooon...

Keep checking for new posts till then HaPPy Reading.

ChEEeeerS

Telecom Tigers Team

telecomtigers@gmail.com
http://homepageforu.webs.com/

HANDOVER IN 3G

2011-07-27T16:49:00.003+05:30

Hi All

Here is the detail for different type of handovers in 3G.

UMTS Handover

There are following categories of handover (also referred to as handoff):

• Hard Handover

Hard handover means that all the old radio links in the UE are removed before the new radio links are established. Hard handover can be seamless or non-seamless. Seamless hard handover means that the handover is not perceptible to the user. In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover.

• Soft Handover

Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN. Soft handover is performed by means of macro diversity, which refers to the condition that several radio links are active at the same time. Normally soft handover can be used when cells operated on the same frequency are changed.

• Softer handover

Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (i.e. the site of co-located base stations from which several sector-cells are served. In softer handover, macro diversity with maximum ratio combining can be performed in the Node B, whereas generally in soft handover on the downlink, macro diversity with selection combining is applied.

Generally we can distinguish between intra-cell handover and inter-cell handover. For UMTS the following types of handover are specified:

• Handover 3G -3G (i.e. between UMTS and other 3G systems)

• FDD soft/softer handover

• FDD inter-frequency hard handover

• FDD/TDD handover (change of cell)

• TDD/FDD handover (change of cell)

• TDD/TDD handover

• Handover 3G - 2G (e.g. handover to GSM)

• Handover 2G - 3G (e.g. handover from GSM)

The most obvious cause for performing a handover is that due to its movement a user can be served in another cell more efficiently (like less power emission, less interference). It may however also be performed for other reasons such as system load control.

• Active Set is defined as the set of Node-Bs the UE is simultaneously connected to (i.e., the UTRA cells currently assigning a downlink DPCH to the UE constitute the active set).

• Cells, which are not included in the active set, but are included in the CELL_INFO_LIST belong to the Monitored Set.

• Cells detected by the UE, which are neither in the CELL_INFO_LIST nor in the active set belong to the Detected Set. Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state.

The different types of air interface measurements are:

• Intra-frequency measurements: measurements on downlink physical channels at the same frequency as the active set. A measurement object corresponds to one cell.

• Inter-frequency measurements: measurements on downlink physical channels at frequencies that differ from the frequency of the active set. A measurement object corresponds to one cell.

• Inter-RAT measurements: measurements on downlink physical channels belonging to another radio access technology than UTRAN, e.g. GSM. A measurement object corresponds to one cell.

• Traffic volume measurements: measurements on uplink traffic volume. A measurement object corresponds to one cell.

• Quality measurements: Measurements of downlink quality parameters, e.g. downlink transport block error rate. A measurement object corresponds to one transport channel in case of BLER. A measurement object corresponds to one timeslot in case of SIR (TDD only).

• UE-internal measurements: Measurements of UE transmission power and UE received
signal level.

• UE positioning measurements: Measurements of UE position. The UE supports a number of measurements running in parallel. The UE also supports that each measurement is controlled and reported independently of every other measurement.

Keep checking for new posts till then Happy Reading.

Warm Regards
Kushal Mahajan

3G Channels

2011-07-16T17:20:00.011+05:30

Hi All,

Here is the list of different channels used in 3G network for transporting information at much faster speed.

These are divided into Logical, Transport & Physical.

UTRA Channels

UTRA FDD radio interface has logical channels, which are mapped to transport channels, which are again mapped to physical channels. Logical to Transport channel conversion happens in Medium Access Control (MAC) layer, which is a lower sublayer in Data Link Layer (Layer 2).

Logical Channels:

Broadcast Control Channel (BCCH), Downlink (DL).
Paging Control Channel (PCCH), DL
Dedicated Control Channel (DCCH), UL/DL
Common Control Channel (CCCH), UL/DL
Dedicated Traffic Channel (DTCH), UL/DL
Common Traffic Channel (CTCH), Unidirectional (one to many)

Transport Channels:

Dedicated Transport Channel (DCH), UL/DL, mapped to DCCH and DTCH
Broadcast Channel (BCH), DL, mapped to BCCH
Forward Access Channel (FACH), DL, mapped to BCCH, CCCH, CTCH, DCCH and DTCH
Paging Channel (PCH), DL, mapped to PCCH
Random Access Channel (RACH), UL, mapped to CCCH, DCCH and DTCH
Uplink Common Packet Channel (CPCH), UL, mapped to DCCH and DTCH
Downlink Shared Channel (DSCH), DL, mapped to DCCH and DTCH

Physical Channels:

Primary Common Control Physical Channel (PCCPCH), mapped to BCH
Secondary Common Control Physical Channel (SCCPCH), mapped to FACH, PCH
Physical Random Access Channel (PRACH), mapped to RACH
Dedicated Physical Data Channel (DPDCH), mapped to DCH
Dedicated Physical Control Channel (DPCCH), mapped to DCH
Physical Downlink Shared Channel (PDSCH), mapped to DSCH
Physical Common Packet Channel (PCPCH), mapped to CPCH
Synchronisation Channel (SCH)
Common Pilot Channel (CPICH)
Acquisition Indicator Channel (AICH)
Paging Indication Channel (PICH)
CPCH Status Indication Channel (CSICH)
Collision Detection/Channel Assignment Indication Channel (CD/CA-ICH)

Keep checking for new posts till then Happy Reading.

ChEEeeRrS

Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/

Mobile Location Update

2011-06-04T21:33:00.015+05:30

Hi Friends,

Lets discuss something about Location Update Procedure, because of which a mobile user can move freely.

As a mobile user, a person can be anywhere but a network has to keep track of user, in-case if somebody wants to call him, so the transaction that keeps network updated about the subscriber present location is termed as location update.

A mobile phone constantly receives information sent by the network, which includes ID of the VLR area in which mobile is currently located & mobile stores that ID.

Every time the network broadcasts the ID of the area, the mobile compares this information to the area ID stored in its memory. When the two IDs are no longer the same, the mobile sends the network a request, i.e. a registration inquiry to the area it has just entered. The network receives the request and registers the mobile in the new VLR area. Simultaneously, the subscriber’s HLR is informed about the new VLR location and the data concerning the subscriber is cleared from the previous VLR.

There are 3 different kinds of location update procedure like,

Location Registration (power on).
Generic.
Periodic

Location Registration (power on) - Whenever mobile turns ON, location registration takes place, which is also termed as IMSI attach, because as soon as the mobile station is switched on, it informs the VLR that it is now back in service and is able to receive calls, as a result of a successful registration, the network sends the mobile station two numbers that are stored in the SIM (Subscriber Identity Module) card of the mobile station.

Location Area Identity (LAI) – it’s a globally unique number.
Temporary Mobile Subscriber Identity (TMSI) - is used for security purposes, so that the IMSI of a subscriber does not have to be transmitted over the air interface. It’s a temporary identity, which regularly gets changed.

Generic – It happens, if LAI present in mobile SIM & LAI received via control channels during network broadcast are different.

The mobile starts a Location Update process by accessing the MSC/VLR that sent the location data. A channel request message is sent that contains the subscriber identity (i.e. IMSI/TMSI) and the LAI stored in the SIM card.

When the target MSC/VLR receives the request, it reads the old LAI which identifies the MSC/VLR that has served the mobile phone up to this point. A signaling connection is established between the two MSC/VLRs and the subscriber’s IMSI is transferred from the old MSC to the new MSC. Using this IMSI, the new MSC requests the subscriber data from the HLR and then updates the VLR and HLR after successful authentication.

Periodic – It is carried when the network does not receive any location update request from the mobile in a specific time. A timer controls the periodic updates and the operator of the VLR sets the timer value.

The network broadcasts this timer value so that a mobile station knows the periodic location update timer values & when the set time is up, the mobile station initiates a registration process by sending a location update request signal.

The VLR receives the request and confirms the registration of the mobile in the same location area. If the mobile station does not follow this procedure, it could be that the batteries of the mobile are exhausted or the subscriber is in an area where there is no network coverage. In such a case, the VLR changes the location data of the mobile station to “unknown”.

Keep checking for new posts till then Happy Reading.

ChEEeeRrS

Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com

Difference between NGN & TDM Network

2011-03-13T21:21:00.013+05:30

Hi,

In today's scenario, NGN is gradually replacing traditional TDM network,
So below are the some differences / benefits of NGN system w.r.t. traditional TDM

Keep checking for new posts till then HaPPy Reading.

ChEEeeerS

Telecom Tigers Team

telecomtigers@gmail.com
http://homepageforu.webs.com/

MNP SMS Flow

2011-01-04T23:55:00.003+05:30

Hi All,

Greetings from our team!!!

Since MNP started materializing in INDIA, there has been lot of interest growing on MNP call flows. We have received quite a few requests for MNP SMS flow.

Here we have tried to explain basic MNP SMS flow. Terms which came into existence due to MNP are already explained in earlier posts.

So let us start.

Assumptions: A and B both are Vodafone Delhi Subscribers (Ported In or normal).

A is postpaid number.

Let us now go through signalling flow.

1) A sends an SMS to B. Mobile Originated Forward Short Message (MO-FSM) is send to STP/MNP with destination as SMSC address(SMSC GT). SMSC address is already stored in SIM. MO-FSM also contains B number to which SMS is sent.

2) MNP check its database attaches RN/LRN to B number and forward MO-FSM to SMSC.

3) SMSC acknowledges the MO-FSM by FSM Response to MSC. This three steps complete the MO leg of SMS Flow and handset receives an indication "SMS sent" at this point of flow.

4) Step4 marks the beginning of SMS terminating flow. SMSC checks this is our own RN/LRN removes RN from B number and sends Send Routing Info- Short Message (SRI-SM) to STP/MNP. This message can be directly send to HLR also that depends on network topology.

5) SRI-SM is forwarded to HLR with B number.

6) HLR responds SRI-SM Response with the VLR address where subscribers is currently registered and IMSI of B number.

7) On receiving VLR address now SMSC knows where to send MT-FSM. SMSC send MT-FSM to that particular VLR with B number IMSI and SMS data.

Here after MSC tries to deliver this message to B Subscriber using standard MT SMS flow.

8) MSC/VLR acknowledge SMSC by MT-FSM response which contains status of MT SMS.

i.e delivered or failed cause if SMS is not delivered to B number.

This sums the SMS flow in case of MNP,our main motive was to highlight the difference between normal and MNP SMS Flow. Hope we fulfilled that and hope this post was informative for you.

Keep checking for new posts till then HaPPy Reading.

Comments/Criticism/Queries/Appreciations are most Welcome as they are lifeline of this blog.

ChEEEEErS

Telecom Tigers Team

telecomtigers@gmail.com
http://homepageforu.webs.com/

Interview Questions ?

2010-11-28T13:13:00.001+05:30

Hi Friends,

        From now on we are starting a new section, where we share Questions which were faced by us in an Interview & we expect answers from our blog readers (in comments), which will help all of us to Enhance their Knowledge & Remember "Sharing is Caring".

                1. Explain the Basic Unit of Traffic ?

                2. Define term "End of Selection" ?

                3. Role of LRN/RN in MNP ?

                4. why TMSI used for Paging ?

                5. Role of MSRN ?

We'll publish Best Answer Soon, till then Happy Brain Storming

Thanks
telecomtigers@gmail.com
http://homepageforu.webs.com/