One Way Audio on SPA525G to ADTRAN TA9 FXS

[aaronsprigg]

Were having an issue with a SPA525G running 7.4.8, calling a ADTRAN TA9 series FXS subscriber, through a Metaswitch/Acme SBC network.   The call gets setup at 729, the then the 525 starts talking 711 when everyone else is talking 729.  This results in the ADTRAN getting no audio stream.

[Daniele Giordano]

Can you add the syslog trace of the SPA?

What variant of G.729 are used? G.729a, G.729b, G.729ab, etc.

Regards.

[aaronsprigg]

It turns out that the Cisco SPA525G is probably working correctly and is originating the Call at G.711 (its default) and then the Metaswitch/Acme then offers to the ADTRAN TA9, G.729a preferred and G.711.  The ADTRAN TA9 picks G.29a (because its preferened both by), so there is an asynchrnous codec situation in the RTP streams, and the ADTRAN drops the RTP for the G.711 path.

When I change the default in the Cisco to prefer G.29a the calls work as expected.

In the situation where the ADTRAN orignates the call, everything works fine.

So at this point I am not suspecting Cisco SPA525G issues, but I will udate if my vendor tells me otherwise.