Voice call quality degraded for external (incoming & outgoing) calls

[shaharshad]

Hi 

We have Cisco voice set up with Call manager & 2900 at edge(and it is dedicated only for voice traffic). Everything was smooth but  our user experiencing bad call quality (for external calls only whether they call or someone call to them )from last 2 days. User experience is . Within office call quality is fine.  

Few of the things Which i have checked; NMS for traffic congestion but everything normal, all in between devices are as per usual (cpu,memory,traffic in/out,etc), packet drop out(couldn't find any), I checked connectivity from router to service provider (it is less than 100 ms which of course is acceptable and inward to our network to core /dist/access devices via ping etc(with on packet drop 100%). I checked all interfaces of router for any packet drops or layer 2 errors but couldn't find any. No changes have been done recently on call manager and router. 

Can you suggest what else i can do? 

Thanking in advance

[Manish Gogna]

Can you try changing the codec for external calls to g711 as a test ( if it is set to g729 ), you may do it for some specific dial peer as well for testing purpose.

Check if any specific phone models are affected or all  of them. If only a specific phone model is affected then the issue could be specific to that model rather than anything on the network.

If basic network checks have been performed then you may need to engage TAC with PCM captures from the gateway for a test call to understand where the issue is originating from.

http://www.cisco.com/c/en/us/support/docs/voice/h323/116078-technologies-technote-commandreference-00.html

https://supportforums.cisco.com/document/101961/how-troubleshoot-voice-quality-issues-ucm-environment-bad-sound-no-audio

Manish

[shaharshad]

Hi Manish,

Thanks , it's already on 711a. User are experiencing randomly and not a specific device or end switch. User experience sort of voice break(latency) after 2nd min of call.

Thanking in advance

[Manish Gogna]

If its random then you may look at the option of setting up a triggered capture where the users would be informed to dial a specific code on their ip phones if they experience voica quality issue on a specific call. This will allow only the required captures to be collected from the gateway.

Manish

[shaharshad]

Thank Manish,

we have also escalated to our service provider and they suggested to reboot systems and whole network infrastructure once :)

[shaharshad]

Hi,

We are still facing same issue. Actually internal user gets crackling voice whereas external caller/attendee doesn't get that sound. Did generate a TAC and they took logs from external interface and finally they said it is coming from your vendor side. But unfortunately vendor is still denying :). I have those captured packets if you wanna have a look. 

[shaharshad]

Hi,

We contacted for Cisco Support they got voice traffic samples on repeatedly on internal & external legs. They did two things first bind IP and second they removed MTP (for external calls. i.e. in old setup call manager was in between all the time, don't know why). Issue resolved gradually. Cisco guys said issue is on internal leg but couldn't define exact device and why this happened.