[asterisk-users] Send SIP 100 Trying instead of 183 Session Progress

[Richard Revels]

You are probably running into the problem described below.  Below that  
is a link to the original document with the code patch.  I put it on a  
PRI box we use inhouse and it took care of the 183 before a busy for  
me.  However, this is a box we use inhouse.  I've never put it on  
anything in production.  Your mileage may vary

 >>>>>>>>>>>>>>>>>>>>>>
gday guys (n'gals).

I have a third party SIP platform which generates outbound calls via
asterisk to ISDN (Australia - so thats ETSI ISDN).   This platform  
doesn't
really like inband signalling on outbound calls (ie getting 183's with  
SDP
-- its fine with 180 Ringing etc...)

Having had a bit of a silly time with the sip.conf variable
progressinband=never,no,yes (arg!) I dug a little deeper into the  
chan_sip
code.

It appears on a SIP->Zap call the ISDN channel is opened, and before  
you can
say 'boo' sip_write() in chan_sip is called.... this appears to occurs  
prior
to any ISDN signalling (such as PRI_EVENT_PROCEEDING etc..)

sip_write doesn't seem to care at all what progressinband is set to,  
and if
it gets a frame when the SIP channel is not in AST_STATE_UP it  
generates a
183 with SDP (then sets SIP_PROGRESS_SENT)

Does this behaviour seem strange?   I'm not really sure if this is a  
bug, a
'its just like that' thing, or something strange with our ISDN that is
unusual?

In an ideal world (for me anyway... *grin*) I would think that
progressinband=never (or even progressinband=no) would mean that 180
Ringing, 486 Busy etc would be used and 183 Session Progress with SDP  
would
not...

I have done some basic testing and if I patch as follows...
 >>>>>>>>>>>>>>>>>>>>>

url to patch document:
 From ds at seiros.ru Mon May 1 04:41:40 2006 From: ds at seiros.ru ...

Richard


On Dec 21, 2007, at 9:57 AM, Remi Quezada wrote:

> Hi,
>
> I have a Asterisk that connects to the PSTN via a PRI.   After  
> Asterisk
> sends the setup message it immediately sends a 183 Session  
> Progress.  Is
> there a way I can change it so that it sends a 100 Trying instead?
> Because I am having some issues with a equipment where it does not  
> play
> a busy tone as a result of sending a 183 Session Progress then the  
> 486 Busy.
>
> Thanks
>
> Remi
>
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