[cisco-voip] No Audio on MGCP Hairpin

[Jonathan Charles]

To be honest, I have never seen an MGCP hairpin work...

Usually, we bring the PRI in on one gateway and send the QSIG out another.

I am presuming that the problem comes with the fact that the source and
destination IP audio streams are the same, so no audio (do a show call
active voice and confirm this).

My guess is that when you are doing a consultative transfer, the call is
actually terminating elsewhere (PR-PHONE-PRI)

Though I do have a solution for you.

Kill MGCP for the QSIG PRI and use H.323 (keep MGCP for the telco PRI). This
way the call will be coming off of the gateway, going to CCM and back to the
gateway (this will replicate the consultative transfer that does work).



Jonathan

On 12/23/06, Bernhard Albler <balbler at nts.at> wrote:
>
> Hi guys,
>
>
> I currently i have a little issue, someone else might have stunmpled upon:
> MGCP Gateway(2811, running 12.4(8a)), controlled by ccm 5.04-2121. Behind
> the gateway there is a siemens hicom 300 pbx. We are running iso qsig
> between the two systems.
> When using CFA, or a translation pattern inside of ccm, and this results
> in a hairpinned call (in via the mgcp gateway, and out of the same gateway)
> which has no audio. SO neither sides hears anything, signalling is just
> fine.
> If I do a consult. Transfer the same way (e.g. I implemented this with an
> ipcc-x script as a workaround for now), the audio is cut through just fine.
>
> The q931 traces on the gateway show, that both channels seem to be
> connected just fine, a show call active voice shows, that there are still ip
> call legs, both pointing at the ip of the gateway.
>
> Anyone run across this? Am I doing something fundamentally wrong?
>
> Regards
> bernhard
>
>
>
> ------------------------------------------
> DI (FH) Bernhard Albler
> Systems Engineer
>
> NTS Netzwerk Telekom Service AG
> Gastgebgasse 27
> 1230 Wien
>
> Tel: +43 (0) 1/867 67 76-0
> Fax: +43 (0) 1/867 67 76 -56
>
> Web: http://www.nts.at
> email: balbler at nts.at
> ------------------------------------------
> "A doctor can bury his mistakes but an architect can only advise his
> client to plant vines."
> Frank Lloyd Wright
>
>
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