Oneside voice issue through VPN for PSTN calls

[mrfcisco1]

We are using CUCM 8.x and MGCP gateway 3925. After migrating MPLS link from one SP to another we are facing one side voice issue when users call from soft phone or CUPC when they connect through VPN. Soft phone users can hear PSTN user but PSTN caller not able to hear Softphone users. Users able to hear each other when they call internal extensions even though connected through VPN. Anyway call setup is working fine and user able to hear the ring back tone also. But when call answers ther is only one side voice. We are not sure what happened after link migration. Is it a firewall issue ? somebody can help us on this. Thank you

[techguy]

Did u properly configure DSP resources and did u configure codec??? Paste your gateway config.

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[nikshah]

I doubt its a codec issue as the call wouldnt complete. Normally one way audio issues are routing issues.

The very fact that Softphone is able to hear PSTN and vice versa doesnt work prompts me to sniff the egress interface of the router (interface where you have bound yr media traffic) and see if there is a increment with source being the ip add of the cups/cipc.

what changed between yr first and second provider, like ip add, ports etc..

i still think its a network / firewall traffic issue.

[baskaranm]

Hi,

Please go through the below link and check for configuration for softphone

http://www.cisco.com/en/US/products/sw/voicesw/ps1860/products_tech_note09186a0080094ed1.shtml

Regards,

Baskaran.M

[Tracy Larson]

Here is a decent doc to follow for one way voice issues.

http://cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a008009484b.shtml#mgcp_media