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

[Pavel Eremin]

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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