[Freeswitch-users] Codec Negotiation Help

[Michael Collins]

I believe in the scenario you describe that the call would fail since the
incoming call cannot inherit the only codec supported by the b leg device
(GSM).

-MC

On Thu, May 26, 2011 at 10:56 AM, Spencer Thomason <
spencer at 5ninesolutions.com> wrote:

> Thanks for you help, I'll try that.  So I'm a little confused with the
> negotiation process with two profiles.  Lets say for  example that I have a
> device that only supports GSM on the internal profile and a call comes in on
> the external profile as ULAW, G729.  If I set inherit_codec=true would
> Freeswitch then transcode?  How does the disable-transcoding option work in
> regards to two profiles?  I.e. Only one profile has transcoding disabled but
> a call traverses both of them.. (2 legs, one bridge).  Which profile would
> the transcoding need to be enabled (or not disabled rather)?
>
> Thanks,
> Spencer
>
>
> On May 26, 2011, at 11:47 AM, DJB International wrote:
>
> Your profile has late negotion enabled.  I believe you can set
> inherit_codec=true, so that it will force A leg to use the same codec as B
> leg offered.
>
>
> On Thu, May 26, 2011 at 9:04 AM, Spencer Thomason <
> spencer at 5ninesolutions.com> wrote:
>
>> Hello all,
>> I have a problem regarding the codec negotiation on an outbound call.  My
>> setup is like this:
>>
>> Polycom IP 650 (1-n) -NAT-> FS  --> Our Signaling Proxy --> ITSP Proxy
>> ---> ITSP Cisco GW
>>
>> I'd like to use different codecs for different call paths (in order of
>> pref), g729 in passthru only:
>> IP-650         ->  IP-650   G722, PCMU, G729
>> Inbound      ->  IP-650   PCMU
>> IP-650         ->  Outbound PCMU,G729
>>
>> I have two sofia profiles, internal, public IPv4:5060 and external,
>> public:IPv4:5080.
>>
>> The phones use the internal profile and the external profile only
>> communicates with our signaling proxy (no media proxy).
>> On the internal one:
>> CODECS IN               G722,PCMU,G729,GSM
>> CODECS OUT              G722,PCMU,G729,GSM
>> NOMEDIA                 false
>> LATE-NEG                true
>>
>> External:
>> CODECS IN               PCMU,G729
>> CODECS OUT              PCMU,G729
>> NOMEDIA                 false
>> LATE-NEG                true
>>
>> I have inbound-codec-negotiation set to greedy on both profiles and on
>> outbound calls set absolute_codec_string=PCMU,G729 to prevent transcoding.
>>  Note that mod_g729 is enabled for passthru only.
>>
>> The problem I have is this:
>> We use the dynamic routing module in OpenSIPS to select an outbound
>> provider/GW, all support PCMU and G729.  On one of the routes, the Cisco IOS
>> GW on this route has G729, PCMU configured as its codec pref.
>>
>> I have included a ladder diagram to better illustrate the problem but in a
>> nutshell, the polycom negotiates PCMU with FS, FS asks for both PCMU and
>> G729, the cisco GW sends G729 and FS sends a 488 because it can't transcode.
>>  I would like to keep G729 in the outbound prefs because some routes might
>> not support PCMU.  Should I set one of the profiles to generous, and if so
>> which one?
>>
>> When someone makes an outbound call the following happens (ladder
>> diagram):
>> http://pastebin.freeswitch.org/16380
>>
>>
>> Sorry for the novella, :-)
>>
>> Thanks!
>> Spencer
>>
>>
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