[Asterisk-Users] Asterisk and Cisco AS53xx/54xx Access Server Platform

[Kevin P. Fleming]

Tom Samplonius wrote:

>   What does "progressinband" do exactly?  Does it disable 180 responses?
> 
>   I can't find any references to what effect "no", "yes", and "never"
> have on the SIP exhange.  In fact, why is it called "inband" if it
> involves the SIP messages?  Wouldn't "inband" refer to messaging in
> the media stream (RTP)?

What it does is rather complicated... and somewhat non-intuitive.

The setting only affects what happens when an AST_CONTROL_RINGING frame 
is received from the Asterisk core for a channel (which happens when a 
call is being placed and Dial() is generating ringback, or if the 
outbound channel sends ringing indications, or if audio progress 
detection is turned on and it detects audio ringback).

If set to 'yes', and '183 Session Progress' has not already been sent, 
then '180 Ringing' is sent _and_ audio ringback is also generated 
(although I can't seem to figure out how that could work, since if '183 
Session Progress' has not been sent, there is no early media in place).

If set to 'no', and '183 Session Progress' has not already been sent, 
then '180 Ringing' is sent.

If set to 'never', then '180 Ringing' is sent, even if '183 Session 
Progress' has already been sent. This is the default, and was found to 
cause some problems with Polycom phones (at least using firmware 1.3.4).