The command “show call active voice brief” is an engineer’s best friend when it comes to confirming jitter and other call quality issues.

Here is a sample output of the command:

GapFillWithSilence=950 ms
GapFillWithPrediction=1980 ms
GapFillWithInterpolation=0 ms
GapFillWithRedundancy=0 ms
HiWaterPlayoutDelay=350 ms
LoWaterPlayoutDelay=25 ms
ReceiveDelay=29 ms
LostPackets=0
EarlyPackets=0
LatePackets=83

If you see the following values incrementing at a high rate, then you likely have an issue:

• GapFillWithSilence = Choppy voice issues
• GapFillWithPrediction = Synthetic voice issues
• LatePackets = Jitter

Fax passthrough encodes fax traffic with in a G.711 voice codec and sends it across the VoIP network as a voice call. The call may use any codec (G.711, G.729, G.723) etc. initially and once a 2100 Hz CED tone is detected, the device (ATA, for example) tells the far end gateway to switch over to G.711 using a peer-to-peer message. This message is called a NSE message (Named Signalling Event) with in the RTP stream.

Here are the important things to know about NSE-based passthrough for fax faxes and modems:

• The 2100 Hz CED tone played from the terminating fax is the stimuli tone for initiating NSE-based passthrough for normal G3 fax devices. If the DSP on the TGW never detects this tone then the switchover to passthrough will never occur.
• Upon detecting the 2100 Hz CED tone, the TGW initiates the passthrough switchover using an NSE-192 message. The OGW responds with an NSE-192 message.
• The NSE-192 message upspeeds the codec to G.711, disables VAD, and sets the jitter buffer appropriately.
• The NSE-193 is triggered by an ANSam tone that is only found with high speed modem and SG3 fax calls. The NSE-193 signals that the echo cancellers on the voice gateways need to be disabled.

The process is pretty straightforward once you address a few issues.

Issue number one: Paint Selection

William picked a faux gold-plated can of spray paint.  Make sure you select the type of paint that will bond to plastic.

Issue number two: Disassembly

Take some time to understand how the pieces of the 79XX phones lock together.  I found that this article was especially helpful.  The trick to disassembly is to know how the pieces slide apart from one another.  You have to use a fair amount of force in the process.  Knowing which way to pry and pull will ensure that nothing will break.

Issue number three: Spray Paint Application

Be patient in the process!  I was short on time and, as a result, got poor results with the paint.  Make sure that you work in a well-ventilated room and space out applications with plenty of time to allow the paint to dry and cure.  If I were to go back and do it over again, I’d use these as a general rule:

• No more than one application per 24 period
• Do not attempt to pain everything in one application
• Do not apply more than two coats of paint, otherwise the line buttons and soft keys will stick a little since the tolerance is so low between the pieces.

Issue number four: Understand How the Metal Spring is Positioned

I wasted some cycles getting the metal spring on the hook lever.  There’s nothing worse than getting the phone reassembled only to find that the spring came loose.  I found this YouTube video especially helpful as it provides a close-up of the spring.

Issue number four: Avoid Tight Spaces

This point can’t be stressed enough.  I applied the first coat of paint on my three-season porch.  The ventilation was poor and it gave me some nasty symptoms akin to a head cold the following day.  Remember that spray crap is wicked toxic.  Get outside for you application and avoid some chemical fallout.

The result?

I was pretty happy overall.  Yes, I made some mistakes, but it looks cool sitting in my home lab downstairs.  is the final product.

Holy cow, Batman, that's a lot of red!

In between house-hunting, full-time work, studying for an MBA, and have two small kids… [oy vey] …I need to find time for recalling codec bandwidth calculations, FRF.12, digital networking, etc.

Fortunately, there’s a great community out there to help with all your Cisco Voice study needs: IEOC.com.  IEOC.com is a online study resource for INE, the top CCIE Voice training partner out there.  Best part?  It’s free!

The nice thing about IEOC.com is that you have the option to submit/reply to posts through email or web-based forum.  Once you sign up, you can either subscribe to emails or interact directly on the forums.

Mark Snow (CCIE #14073 Voice/Security), Mijanur Rahman (CCIE #27424 Voice) and Matthew Berry…err…me (CCIE #26721 Voice) are active on the forums.  If you post a question, you’ll likely get one of us to respond immediately.  It’s a fun community and I’d like to invite you to join in.

Recommended IEOC Forums:

• CCIE Voice General
• CCIE Voice Technical
• CCNP Voice (formerly CCVP)
• CCNA Voice

To sign up for an account, go ieoc.com.  Once you have an account, join these forums.  They even have regular contests where you can win an iPad for posting.

Free help plus the chance to win an iPad?  Not bad at all!

Test numbers!  If you’ve ever done phone deployments you’re aware of the value of a good test number.

For the past two years, I’ve used +1.800.444.444 for my testing.  It reads your caller ID back to you.  Cool, but I want more.  I want features like:

• Caller ID  playback.  Use this test to trace and label lines in a telephone closet from your butt set in one operation without using your cell phone. The name ID feature helps ID the owner of lines in a crowded NID so you can only install surge suppression on YOUR lines.
• DTMF Echo.  Have you ever called a voicemail system or bank by phone system and not been able to make menu selections? This test helps confirm the source of common “after connect” DTMF dialing issues on VOIP telephone systems and services.
• CO Line Toner.  Use this when you have lost your toner, need tone on a live line, or need additional toners to swap circuits.
• Voice Echo Press.  Test one-way audio effects on VOIP systems.

+1.804-222-1111

That’s the ticket!  Give it a shot.  You won’t be disappointed.

Configure LDAP Filter in CUPS

The customer did not place all end users in a single OU.  As a result, the LDAP profile in CUPS needed to be set to search from the domain down (e.g. domain.local).  As of CUPS 8.6(3), there is no LDAP filter.  When configuring an LDAP profile at the domain level, the CUPC directory search may produce undesirable results such as service accounts or admin accounts.

To resolve this issue, an LDAP filter must be inserted into the search context field.  This is accomplished using a semi-colon + [filter] following the search context.   The following example mimics the best-practice standard in CUCM of filtering users by the ipPhone field.

Syntax: DC=domain,DC=local;&(ipPhone=*)

Search Multiple OUs in LDAP

In some cases, it will be necessary to search multiple OUs to find the necessary end-users.  Separate multiple LDAP search contexts with a # (or hash) character.  The following example search Sales and Support OUs:

Syntax: CN=Sales,DC=domain,DC=local#CN=Support,DC=domain,DC=local

Recommended LDAP Search Filter

The most effective LDAP search filter that I have found so far is the following:

Syntax: (&(objectclass=user)(!(objectclass=Computer))(!(UserAccountControl:1.2.840.113556.1.4.803:=2))(ipPhone=*))

This filters where the object:

• Is an end-user
• Is not a computer
• Is not disabled
• Has the ipPhone field populated with any value

In spite of deleting the VPN application from my Applications folder, I still saw error messages in the console log.  This bothered the OCD part of me.

Today, I came across the instructions to completely uninstall that VPN client.  I’ve included them below for your (and my) future reference:

1. Open your hard drive.
2. Double-click Applications > Utilities > Terminal.
3. On the Terminal screen, type cd / (that is, “cd”, followed by a space, and then “/”).
4. Press Return.
5. Type cd /usr/local/bin (that is, “cd”, followed by a space, and then “/usr/local/bin”).
6. Press Return.
7. Type ls and press Return. Verify that vpn_uninstall is in the list results.
8. Type sudo ./vpn_uninstall (that is, “sudo”, followed by a space, and then “./vpn_uninstall”).
9. Press Return.
10. At the Password prompt, type in your administrator password and press Return. Note: no characters will show up when you type your password, but it accepts whatever you type in.
11. A prompt to confirm deletion will appear. Type yes and press Return.
12. A second confirmation prompt will appear. Type yes and press Return.
13. Once the process has completed you will see the following message: “Cisco Systems VPN client uninstall completed successfully.”
14. Type exit and press Return. This will log you out of the Terminal.
15. Quit Terminal.