Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Gaps / Jitter


I was troubleshooting an audio problem, in a CS2610, VIC-2B S/T, with c2600-mz-12-1.9.bin, and experienced incremental "gaps" with the "Show call active voice brief" command.

After reading Cisco Output Interpreter, they had advised to configure the "playout-delay" command in Voice-Port or Dial-peer interfaces.

The problem is, that this command is not aceptable on this IOS, and i wont be able to change it, by client requirements.

Any sugestions?


Prerequisites of PlayOut-delay command

* Cisco IOS Release 12.1(5)T or greater

Best Regards,



Re: Gaps / Jitter

upgrade the IOS.

Try the following steps:

Set the codec complexity to high using the codec complexity command.

Turn off the adaptive de-jitter buffer operation using the playout-delay mode command.

Adjust the nominal playout-delay to 250 ms.

Note: Nominal playout-delay is the amount of delay applied at the beginning of a call by the jitter buffer in the gateway, in milliseconds. In fixed mode, this is also the maximum size of the jitter buffer throughout the call.

This is an example configuration:

voice-card 1

codec complexity high

voice-port 1/0/0

playout-delay mode fixed

playout-delay nominal 250

This configuration results in an initial lag on the call, but after that there is enough in the buffer to playout a continuous audio stream. In this instance, the voice clarity is satisfactory.

Note: Depending on the severity of the delay and jitter characteristics of the network, these actions may or may not resolve the problem.

Note: Before Cisco IOS Software Release 12.1(5)T, the playout-delay command was configured only in voice-port configuration mode. For Cisco IOS Software Release 12.1(5)T and later, in most cases, playout-delay should be configured in dial-peer configuration mode on the VoIP dial peer that is on the receiving end of the voice traffic that is to be buffered. This dial peer senses network conditions and relays them to the Digital Signal Processors (DSPs), which adjust the jitter buffer as necessary. When multiple applications are configured on the gateway, playout-delay should be configured in dial-peer configuration mode. However, when there are numerous dial peers to configure, it might be simpler to configure playout-delay on a voice port. If conflicting playout-delay values have been configured on a voice port and on a dial peer, the dial-peer configuration takes precedence.

New Member

Re: Gaps / Jitter

Thak you for your reply.

As i wrote before i cant upgrade this ios software, cause my client have many (+/-900) sites with same hw/sw configuration, and as far as i know, this is the only with this "gap" problem.

Ty for your effort, but cant solve my problem with the ios upgrade.

Hope someone could show me a workaround on this.

Best Regards,

Bruno Petronio