Hi Matthew,

you do not need to look into the media part, as you can "spot" the FAX 
presence via the re-INVITE with T38 codec in SDP (you can detect it from 
opensips cfg).

So, maybe using the b2b module for something like:
    - allow the voice call to be setup via the b2b in a transparent way
    - if the re-INVITE wth T38 is received from GW, b2b will close the 
leg to the users UA and create a new leg to something able to handle the 
fax - of course, the b2b will bridge the existing leg (towards PSTN) and 
the new leg.

Regards,
Bogdan


Matthew S. Crocker wrote:
> Can OpenSIPS make routing decisions based on the SDP information in an INVITE?
>
> Lets say I have the following config
>
> PSTN -> t.38 Gateway -> OpenSIPS ->  UserAgent
>
> I have a TN from the PSTN routed to the UserAgent,  I'd like to provide a 
> service so the user can use the TN for both voice & faxing.
>
> Voice call goes through normally (g.711 g.729 codec)
>
> Fax call starts off as a normal voice call (INVITE, 180, 183, 200).  Once the 
> call is answered the originating end (PSTN) starts sending fax tones. The 
> Gateway hears the fax tones and attempts to RE-INVITE with T.38 in the SDP.  
> I'd like OpenSIPS to see the T.38 capability in the SDP and redirect the call 
> to a fax->e-mail gateway.  So,  the 2nd INVITE comes in, OpenSIPS sends the 
> INVITE to the fax gateway and a BYE to the user.  The fax gateway does a 200 
> and negotiates T.38 with the PSTN gateway.
>
> I know I can route the call through Asterisk and have it do a quiet answer 
> and listen for the modem sounds.  I'd like to avoid using Asterisk for all 
> RTP traffic and only use it for the fax gateway traffic (i.e. once it has 
> been determined to be a fax Asterisk steps in and handled the T38 -> E-mail)
>
> -Matt
>
>   


-- 
Bogdan-Andrei Iancu
www.voice-system.ro


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