[Asterisk-Dev] ringback after PlayBack()

[Kevin P. Fleming]

Guo-Wei Chiuan wrote:

> My goal is to indicate RINGING upon a caller channel in RING state by using
> "180 Ringing" after 183 is ent.
> However, according to source codes, after 183 is sent(in my case, due to
> Playback() is done), Asterisk would not send "180 Ringing". That is what I
> am trying to figure out.....
> 
> Maybe I shall look up RFC3960. Any ideas?

Once '183 Session Progress' is sent, it is not useful to send '180 
Ringing' any longer... the 183 message informs the endpoint that future 
progress indications for this session will be provided inband via the 
audio stream. Most (if not all) SIP endpoints would ignore any 180 
received after a 183 anyway.