[OpenSIPS-Users] T38 and changing media port for T38 SDP

[Julian Yap]

Hi Pavel,

Yeah, in my example, the media port is changed on the T38 reinvite.
Isn't RTPProxy meant to handle this port change?

- Julian

2010/7/3 Pavel Eremin <pavel at eremina.net>:
> you may change and control content of SDP body by module "textops". So, if
> port is change you may change it back or log it or smth else...
> i use it when Broadworks change media port for G711 to 0...
>
> Julian Yap <julianokyap at gmail.com> писал(а) в своём письме Sat, 03 Jul
> 2010 03:37:48 +0600:
>
>> Any help greatly appreciated!
>>
>> I'm having problems with a T38 UA which changes port when negotiating
>> T38 media.  All the other UA's I've encountered thus far use the same
>> RTP port throughout.
>>
>> I'm also using RTPProxy.
>>
>> In the final 200 OK SDP, the UA changes media port from 49200 to 49152
>> but this changeover isn't detected and the media is sent back to port
>> 49200 so the call then fails to negotiate T38 properly.  Not sure how
>> to log the port changes to further debug this issue as well.
>>
>> Here is the flow:
>> | UA                | OpenSIPS          | T38 GW            |
>> |         INVITE SDP ( g711U)           |                   |
>> |(5060)   ------------------>  (5060)   |                   |
>> |         100 Trying|                   |                   |
>> |(5060)   <------------------  (5060)   |                   |
>> |                   |         INVITE SDP ( g711U)           |
>> |                   |(5060)   ------------------>  (5060)   |
>> |                   |         100 Trying|                   |
>> |                   |(5060)   <------------------  (5060)   |
>> |                   |         180 Ringing SDP ( g711U)      |
>> |                   |(5060)   <------------------  (5060)   |
>> |                   |         200 OK SDP ( g711U)           |
>> |                   |(5060)   <------------------  (5060)   |
>> |                   |         RTP (g711U)                   |
>> |                   |(11392)  <------------------  (14110)  |
>> |         RTP (g711U)                   |                   |
>> |(49200)  <------------------  (10878)  |                   |
>> |         180 Ringing SDP ( g711U)      |                   |
>> |(5060)   <------------------  (5060)   |                   |
>> |         RTP (g711U)                   |                   |
>> |(49200)  ------------------>  (10878)  |                   |
>> |                   |         RTP (g711U)                   |
>> |                   |(11392)  ------------------>  (14110)  |
>> |         200 OK SDP ( g711U)           |                   |
>> |(5060)   <------------------  (5060)   |                   |
>> |         ACK       |                   |                   |
>> |(5060)   ------------------>  (5060)   |                   |
>> |         RTP (g711U)                   |                   |
>> |(49200)  ------------------>  (10878)  |                   |
>> |         RTP (g711U)                   |                   |
>> |(49200)  <------------------  (10878)  |                   |
>> |                   |         200 OK SDP ( g711U)           |
>> |                   |(5060)   <------------------  (5060)   |
>> |                   |         RTP (g711U)                   |
>> |                   |(11392)  ------------------>  (14110)  |
>> |                   |         ACK       |                   |
>> |                   |(5060)   ------------------>  (5060)   |
>> |         200 OK SDP ( g711U)           |                   |
>> |(5060)   <------------------  (5060)   |                   |
>> |         ACK       |                   |                   |
>> |(5060)   ------------------>  (5060)   |                   |
>> |         RTP (g711U)                   |                   |
>> |(49200)  ------------------>  (10878)  |                   |
>> |         RTP (g711U)                   |                   |
>> |(49200)  <------------------  (10878)  |                   |
>> |                   |         ACK       |                   |
>> |                   |(5060)   ------------------>  (5060)   |
>> |                   |         INVITE SDP ( t38)             |
>> |                   |(5060)   <------------------  (5060)   |
>> |         INVITE SDP ( t38)             |                   |
>> |(5060)   <------------------  (5060)   |                   |
>> |         200 OK SDP ( t38)             |                   |
>> |(5060)   ------------------>  (5060)   |                   |
>>
>> This is where it sends the 200 OK with a different media port.
>>
>> - Julian
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>
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