(1) Short problem description:
Not possible to set up 3-way call using all permutations of 3 parties
(2) Longer problem description (what happens):
When settings up a 3-way call between parties A, B and C, not all
permutations work:
- A calls B. B then calls C and connect the two legs.
Works!
- A calls B. A then calls C and connect the two legs.
Works!
- A calls B. C calls A and A connect the two legs.
Does not work!
- A calls B. C calls B and B connect the two legs.
Does not work!
79x0's will only join two call legs in a conference where both call
legs are using the same Call-ID, thus why the phone has a distinction
between adding another call and conferencing someone in. This is so you
can remove yourself from the call and get the two endpoints to talk to
each other using "REFER"'s as per a call transfer. This is actually
documented somewhere.
Of course, that doesn't mean you can't conference two parties in and
just not be able to join them together if you remove yourself from the
call first.
Clearly someone has thought about this possibility in the future - you
may note that in an attended (non-blind) transfer, the phones issues a
"Replaces" header that includes Call-ID and from and to tag, which
allows verification of involvement (or at least sniffing in the path
:-) in the other call leg. This implies that lack of matching Call-ID
is not actually the show-stopper in joining calls implied in the
documentation.
Refer-To:
sip:205@iagu.net?Replaces=0007ebcd-cb61009c-713d5808-39f3a707%40203.32.153.142%3Bto-tag%3D0007ebf0f3e8054d64edeec5-63232610%3Bfrom-tag%3D0007ebcdcb6100352ef9bca5-3cc900fa
(7) Would you classify this as:
(C) Bug/malfunction: Ok to
deploy with workaround.
(9) Contact Information:
Bill Woodcock <woody@SPAM.pch.net>
Andrew Rutherford <andrewr@SPAM.iagu.net>
(11) Report:
Via phone in June 2003.
Message-Id: <p05200f05bb467c98eb1e@[203.32.153.85]>
Date: Fri, 25 Jul 2003 16:00:09 +0930