[Serusers] IP Centrex features

Jiri Kuthan jiri at iptel.org
Tue Dec 2 01:18:14 CET 2003


At 10:54 PM 11/26/2003, Olle E. Johansson wrote:
>Just found an IETF draft on how to implement PBX features in SIP
>http://www.voip-info.org/tiki-index.php?page=SIP+PBX+functions
>
>Maybe we can try to implement these in SER and document these functions
>on the Wiki?

documenting is a great thing to do. draft-ietf-sipping-cc-framework
may provide you with some very reasonable text.

implementation is not necessarily fature of SER -- it is frequently
a feature of end-devices (ED).


>There's some of these in the source examples and in the howto's, but it
>might be good to document functions one by one.
>
># Call Hold

ED feature, specified in the basic SIP spec (there is a difference in
SDP usage between obsoleted and current SIP spec)

># Music on Hold

ED feature.

># Unattended Transfer
># Attended Transfer

ED feature. there is an internet draft specifying use of REFER
for call transfer. (I'm off-line and can't look it up for you,
but all of that should be somewhere at www.iptel.org/ietf)

># Consultation Hold

ED feature

># Unconditional Call Forwarding

a way to do so is to set up permanent UsrLoc entry using SerWeb.

># No Answer Call Forwarding
># Busy Call Forwarding


Currently, voicemail examples in the 'examples' directory are closest.
(We don't have individualized forwarding preferences yet.)


># Single-Line Extension
># Call Pickup
># Call Park

I'm not sure how to do it easily -- I suspect it would take quite
some call control. Having all telephones rung is as easy as forking,
but having one of them joined a conversation entered by another one
may be tricky.

># 3-way Call

end-device feature (e.g., cisco and mitel have three party conferencing).
If two calls in parallel is in conflict with available bandwidth, one
could take a network conferencing server too.

># Incoming Call Screening
># Outgoing Call Screening

one can configure accounting to generate records for serweb.

># Find-Me

parallel forking is turned on by default. (if that implements what
"find-me" is called)

># Automatic Redial

I would say that's an ED feature. There are some drafts specifying 
subscribtion  to call state but I think that having the phone tried
regularly is simpler and does not introduce dependency on
a rarely implemented feature.

-jiri





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