[SIPForum-discussion] SIP 180 ringing

[Olle E. Johansson]

8 maj 2012 kl. 22:25 skrev John Downing:

> Hi Walid:
> 
> A 183 call progress from the PSTN gateway is normal.  You would not expect a 180.  The 183 should have an SDP attached to allow one way RTP audio.  The call progression indicators from the PSTN (ringing, busy, etc) are then presented to the caller.
> 
> We setup these test calls and troubleshoot them in our SIP Training class.  
> 
> http://www.trainingcity.com/course_outline_detail.asp?courseid=2004

I've stated many times on this list that I think that this is wrong and bad practise. Operators should
indicate a change to ringing state by sending 180, not 183, with an sdp. If they want to indicate
busy, they send a busy code and do not do that by only sending 183.

It is important to tell the other side about state changes in signalling. By using 183 for ringing and busy you are hiding important state changes that we may want to indicate by other means than audio.

/O

> 
> On Tue, May 8, 2012 at 5:35 AM, Walid Hbiriq <hbiriq.walid at gmail.com> wrote:
> Hello all,
> 
>  
> 
> I have the following problem :
> 
>  
> 
> -          When testing output calls ,we can’t receive SIP message 180 ringing in the trace (wireshark),we have only 183 progress ?
> 
> -          The call proceed like this operator x => SBC => operator y
> 
> Can anyone tell me what can be the reason?
> 
> 
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> 
> 
> -- 
> Thanks... John
> 
> John Downing
> John at TrainingCity.com
> 613-435-1170 (w)
> 613-883-1235 (c)
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> 
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* Olle E Johansson - oej at edvina.net
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