[Kamailio-Users] dialog enhancements #1

[Iñaki Baz Castillo]

2009/2/4 Daniel-Constantin Mierla <miconda at gmail.com>:

> There is now a new function called dlg_bridge(From, To, outbound_proxy).
> It can be used to connect From and To users. The mechanism is a simple
> call transfer scenario.
>
> kamailio => INVITE (hold) =>From
> kamailio <= 200ok <= From
> kamailio => REFER (To) =>From
> kamailio <= 200ok <= From
> ...
>  From => INVITE ... =>To
> ...
> kamailio => BYE =>From
> kamailio <= 200ok <= From


Hi Daniel, this seems to imitate the mechanism in RFC 3725 (Third
Party Call Control).
Have you considered using initial REFER? It's widely *not* supported
by common phones, but it would be a first step to improve SIP world :)

Please read the thread I opened some days ago about "Initial REFER vs
RFC 3725 (Third Party Call Control)" in SIP-Implementors:
  https://lists.cs.columbia.edu/pipermail/sip-implementors/2009-January/021485.html

Of course, initial REFER wouldn't work in most of the cases, but I
have a "custom" solution:

REFER initial-dialog is much cleaner than INVITE of 3PCC, but it's
usually not allowed by common phones. So a PBX or
SIP server implementing click2dial could try first a REFER
initial-request, and in case it receives a negative response (i.e.
"403 Forbidden" or "501 Not Implemented") the the server could use the
3PCC INVITE.

BTW I'm trying to convince some vendors (softphones basically) to
allow initial REFER (asking permission for the phone user, of course).
 :)

Regards.


-- 
Iñaki Baz Castillo
<ibc at aliax.net>