[Kamailio-Users] basic SIP forwarding with Asterisk

Jeff Brower jbrower at signalogic.com
Fri Oct 23 17:01:41 CEST 2009


Klaus-

> So you want to do transcoding in rtpproxy using a DSP card? I do not
> know - better ask on the rtpproxy mailing list (or Maxim directly - I
> think he has a non-open source solution).

Ya we have -- and it works, no problem.  We've tested already with Kamailio + rtpproxy.

> Anyway - why not do the transcoding in Asterisk?

Because Asterisk is too limited.  It can't do enough channels for G729, and doesn't have good options for codecs like
EVRC and GSM-AMR.

But anyway my question is about SIP with Kamailio + Asterisk, not RTP.  Is there a way that Kamailio can "pass thru"
SIP messages from Asterisk?  Or does each call have to be relayed; i.e Asterisk sets up a call to Kamailio, then
Kamalio sets up a call to the endpoint?

I know that we can get it to work one way or another, but I'm worried about channel capacity if both Asterisk and
Kamailio run on the same server.  "Duplicating" calls does not seem efficient.

-Jeff

> Jeff Brower schrieb:
>> All-
>>
>> Can we use Asterisk combined with Kamailio as follows:
>>
>>           __________             ___________
>>          |          |           |           |
>>   SIP ___|          |___ SIP ___| Kamailio  |___ SIP
>>          |          |           | rtpproxy  |
>>          | Asterisk |           |     |     |
>>          |          |           |     |     |
>>   RTP ___|          |___ RTP ___| DSP card  |___ RTP
>>  (G711)  |__________|   (G711)  |___________|   (G729,
>>                                                  G723,
>>                                                  GSM-AMR,
>>                                                  EVRC)
>>
>> We've already implemented an rtpproxy interface to the DSP card, which has its own GbE port.  Our question is
>> whether
>> we can we perform some type of basic SIP forwarding or "SIP pass-thru", but still invoke rtpproxy for call setup and
>> tear-down and/or when media attributes for the call change?
>>
>> We're getting a lot of requests from customers who -- for whatever reasons -- need to use or continue to use
>> Asterisk,
>> but need to also add transcoding, ec, encryption, and other compute-intensive requirements that Asterisk doesn't
>> support (or at least doesn't support at higher capacity or without going unstable).
>>
>> Thanks.
>>
>> -Jeff
>>
>>
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>




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