Re: [sipx-users] ITSP call goes through but no audio
On Thu, 2009-07-02 at 12:59 -0400, Matt Keys wrote:
>
> I'm testing a SIP trunk to Covista Communications. I'm able to receive
> and send calls but there's two catches:
>
> 1. Placing a call from internal to my cell phone, I do not hear ring
> tones but the cell phone will ring and caller ID is shown properly. If
> I answer the cell I do not hear any audio in either direction however
> according to captures and the phones the call is connected.
>
> 2. Inbound calls (cell phone to internal) I hear a ring tone and also
> see correct caller ID but there's still no audio after answering.
> Again, all appears normal on captures and the phones.
>
> RTP captures are showing a difference in codecs. G.711 on outbound,
> example:
>
> 22.588943 172.16.1.200 -> 172.16.1.2 RTP PT=ITU-T G.711 PCMU,
> SSRC=0x94955FF, Seq=27757, Time=688410696
>
> and G.729 inbound, example:
>
> 6.758089 172.16.1.200 -> 172.16.1.2 RTP PT=ITU-T G.729,
> SSRC=0x3CA4274A, Seq=25643, Time=1257971077
>
> Could this be the problem?
There is no rule that says codecs must be the same in both directions.
I doubt this is your problem - it is much more likely a NAT traversal
issue. Is Covista Communications doing any NAT compensation on their
end - if so, see if you can turn it _off_ so that only one end is
compensating for the NAT.
