Troubleshooting one way voice, only affects single caller

[nlau]

Trying to troubleshoot troubleshoot an issue where the receiver can hear us but we can't hear them. If they call back and we are able to hear each other fine. Outgoing calls from any phone outside our phone system works fine. How would I start troubleshooting this?

We are using CUCM 10.5.2 and the gateway is MGCP

[saurabh94]

Hi 

Which gateway platform are you using

[nlau]

It's a Cisco 2901 with a PRI

[saurabh94]

Hi 

There are few things i need some more insights.

--Outgoing calls from any phone outside our phone system works fine

what i could understand is when phones registered to your CUCM make a call to PSTn using the above gateway with PRI . then receiver can hear you but you can't hear them. in order to troubleshoot this

--verify that signalling is correct.

--you can take a TDM capture on PRI port to isolate the problem if PSTN or internal IP.

Then we can discuss about it.

(rate if helpful)

[nlau]

Thanks, would you happen to have steps on doing a TDM capture?

[saurabh94]

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/voiceport/configuration/15-mt/vp-15-mt-book/voi-pcm.html

Copy it in flash/ rather than TFTp server . 

(rate if this helps)

[nlau]

Alight, was able to do the capture and now I have a .dat file? 

[saurabh94]

Hi 

 you can try following answers on this link

https://supportforums.cisco.com/discussion/11248656/how-play-pcm-capture

and attach the .dat file , will also try to decode it and provide me with a call flow diagram.