[OpenSIPS-Users] media_exchange_from_uri

[M S]

For anyone who comes across this post in future - this is a bug in 3.1 and
above (probably when topology hiding is used) which seems to have been
fixed in 3.4
A workaround is to keep the SDP from caller or callee and send it as the
third variable of media_exchange_from_uri function to establish the
connection correctly.

On Sun, Sep 7, 2025 at 8:34 PM M S <medeanwz at gmail.com> wrote:

> A(caller) <=> B(opensips) <=> C(callee)
>                       B(opensips) <=> D(media server)
>
> I tried it with the "callee" leg in media_exchange_from_uri too.
> technically, the B machine in the middle should send the ip/port of A and D
> to each other in SDPs to make sure media is direct between A and D - but B
> to D invite always has the B's ip/port in it. It should be due to something
> in my script, but what could it be?
>
> On Sun, Sep 7, 2025 at 7:03 PM M S <medeanwz at gmail.com> wrote:
>
>> Hi list,
>> I am trying to use media_exchange_from_uri to play hold music. I use the
>> sample code from opensips blog:
>>
>> if (has_totag() && is_method("INVITE")) {
>>     # catch the on-hold re-invite
>>     if(is_audio_on_hold()) {
>>         if (media_exchange_from_uri("sip:moh at media.server.ip"))
>>             exit;
>>     } else {
>>         # call has resumed - terminate any ongoing media played
>>         media_terminate();
>>     }
>> }
>>
>>
>> But the behaviour is strange.
>>
>> A invite comes to proxy B, rtpproxy is engaged and invite is sent to C
>>
>> A,Aport <=> B,Bport1 - B,Bport2 <=> C,Cport
>>
>> A pressing hold: Invite with a=sendonly is received. With the above configuration, B sends an INVITE (B ip and Bport1) to media.server.ip (D).
>>
>> Media server D responds with 200 OK (D ip and Dport). Opensips B2B sends D,Dport SDP to C (so C expects to receive RTP from D port).
>>
>> While C expects to receive RTP from D directly, D has exchanged SDP with B and therefore sends RTP to B!
>>
>> Why is this happening?
>>
>>
>> Thank you :)
>>
>>
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