[Asterisk-Users] SUBSCRIBE in chan_sip - anyone?

[Clif Jones]

I haven't taken the time to reverse engineer this on * but subscribe is 
used in SIP for serveral things:
1. Message Waiting Indicator (MWI).  Asterisk seems to send out a NOTIFY 
even with no SUBSCRIBE
    though. :)
2. SIMPLE (SIP Instant Message & Presence Leverage Extensions).  The 
SUBSCRIBE/NOTIFY is
   used for the "presence" portion of this.  The Windows Messenger and 
MSN Messenger 4.6/4.7 support
   a pseudo-standard form of this.  We use this our development for 
"phone" presence/status and for
   attendant console.  It is pretty cool but there are scalability issues.

Olle E. Johansson wrote:

> Rich Adamson wrote:
>
>>> So, what hardware or use is the SUBSCRIBE method used for in 
>>> chan_sip.c?  I asked this question a while ago, and got resounding 
>>> silence.  Maybe someone who is better at de-tangling C code than I 
>>> am could take a peek.
>>
>
>> Not sure, but seems to me it came in about the time Olle and Snom 
>> were talking, and Olle was working on sip-2 or something like that.
>
>
> There is support for SUBSCRIBE in the SIP channel. I've been spending
> time trying to understand this and also asked questions with no answer.
>
> My guess is that you can subscribe to an extensions (not sip device) 
> status
> and get notificiations when the status changes. Would be useful for
> phones that have line indicators. There's some authorization for doing 
> this,
> but no ACL list - who can subscribe to what?
>
> Sorry for an unclear explanation, I haven't been able to test with any
> device. Anyone that knows any device that supports SUBCRIBE this way?
>
> BTW, isn't SUBSCRIBE also used for SIMPLE, instant messaging?
>
> /O
>
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