[Freeswitch-users] Transcoding / Call-Hold issue

Carsten Bock carsten at ng-voice.com
Thu May 7 08:11:54 UTC 2020


I am running a FreeSwitch 1.10 (built Debian Packages from the GIT-Branch
due to some codec issues; AMR/AMR-WB is only available, if the respective
libraries are present on the system).

I am using FreeSwitch in the most simple configuration: FreeSwitch is
acting as a (transcoding) B2BUA with only a single peer (Kamailio, which
does the further distribution, Sofia Config attached), so my dialplan is
straight forward and contains a single action:

<action application="bridge" data="sofia/internal/${destination_number}@

Here  is, what I've noticed and where I am unsure, how to fix this:

1) Call from A is sent to FreeSwitch, with Codecs AMR and AMR-WB
2) Call is leaving FreeSwitch towards B, offering Codecs AMR, AMR-WB, G722,
G711, ... B-Party is selecting G722, as it does not support AMR or AMR-WB,
3) Call is connected to A on AMR/AMR-WB and to B using G722

- so far, everything is fine -

Now the following happens:
4) A puts the call on hold, so a INVITE with according SDP is sent to
5) FreeSwitch itself sends an INVITE to B indicating the recognized "Hold"
with according SDP, however now this INVITE only contains AMR-WB, which was
initially offered to B, but which was never responded or even indicated
support for (!?!??!)

I can hardly believe, I am the first one to see this. Does anyone know
where or what to look for and what might have gone wrong here?


P.S.: The first mail didn't go through, as I added my Sofia Config....
without any notice.
Carsten Bock I CTO & Founder

ng-voice GmbH

Trostbr├╝cke 1 I 20457 Hamburg I Germany
T +49 40 524 75 93-40 | M +49 179 2021244 I www.ng-voice.com

Registry Office at Local Court Hamburg, HRB 120189
Managing Directors: Dr. David Bachmann, Carsten Bock
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