[Spce-user] General questions

Daniel-Constantin Mierla miconda at gmail.com
Sun Feb 13 06:05:29 EST 2011

On 2/11/11 7:45 AM, Jon Bonilla (Manwe) wrote:
> El Fri, 11 Feb 2011 00:52:53 +0100
> Daniel Tiefnig<dtiefnig at sipwise.com>  escribió:
>>> 6.       Is it possible to force a ring-back tone to the callee?
>>> Right now there is silence until the call is connecting to pstn (pap2
>>> test device)
>> Well I guess this is intended, as the ring-back tone should occur only
>> when the destination device is ringing... Should be possible with a
>> kamailio config change, like sending a "180 ringing" instead of - or
>> right after - the "100 trying", the SIP guys around here will know that.
> For this purpose you'd need a b2bua able to send 180 or 183 back. But this is
> never a good idea.
Actually to send 180 Ringing you don't need any b2bua, you can do it in 
kamailio config file, just add next line for the INVITEs going to the 
problematic gateways:

send_reply("180", "Ringing");

I did it 1-2 times in the past to fix the situation of similar broken 
gateways that never sent back ringing reply.

> I've seen people using asterisk that configure their dial command with the "r"
> option to fake the ringback tone while making the call. The problem here is
> that the caller thinks the other side is ringing. If for example you're calling
> a cellphone and you get an early-dialog message back like "this subscriber is
> not available at this moment", you hear the message mixed with the ringback
> tone!!

Such audio message is sent after a 183 Session in progress and the phone 
should suppress its own generated ringing tone (due to 180) when it 
receives media. I haven't seen any mixture problem so far. Think also 
about parallel forking when a phone is getting many 180s and 183s for 
the same call. It is phone decision what to play in the speakers.


Daniel-Constantin Mierla

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