Discussion:
Thoughts on multiple registrations to an extension
Sidney San Martín
2009-10-11 22:33:39 UTC
Permalink
Disclaimer: I'm not involved in the SIP community and not very
familiar with its implementation or history.

Whenever I use an IP phone, I run into a nned to register the same
extension on multiple devices, and I always get the recommendation to
create more extensions and use hackery on the PBX to make 'em work
like they're a single one. That's not good enough. The other protocols
we use to communicate (XMPP, POP/IMAP/SMTP, even proprietary ones like
AIM and old ones like POTS) are all friendly to multiple connections
to the same account. Why's this functionality missing from SIP? There
are only a few use cases, but they're huge ones:

- A user has a desk phone but also wants to take and place calls
occasionally from a computer or mobile device over cellular data.
Usually, the desk phone will be the only device registered.
- A user wants an extension represented in two or more geographically
separate locations, say on a desk phone at home and a desk phone at work
- A house with extensions in several rooms. Right now, the "IP" part
of IP telephony usually evaporates inside the home, where SIP gets
bridged to POTS. That's great for retrofits, but as fewer people
subscribe to landline service, there will come a time when new homes
aren't wired for POTS. At the same time, many new homes ARE being
wired with Ethernet.

What do you all think about this problem? (If it's already been
discussed to death, feel free to lightly whack me over the head and
point me to the right thread :).)
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Attila Sipos
2009-10-12 11:37:26 UTC
Permalink
In SIP, one can register multiple devices to the same extension.

Then the call gets forwarded to each device simultaneously using SIP "forking".

from RFC 3261
A proxy server can
also send an INVITE to a number of locations at the same time. This
type of parallel search is known as forking.

It's well-understood, well-known and has been around for several years.

(SIP forking is not possible on stateless proxies though)

Regards

Attila



-----Original Message-----
From: sip-***@ietf.org [mailto:sip-***@ietf.org] On Behalf Of Sidney San Martín
Sent: 11 October 2009 23:34
To: ***@ietf.org
Subject: [Sip] Thoughts on multiple registrations to an extension

Disclaimer: I'm not involved in the SIP community and not very familiar with its implementation or history.

Whenever I use an IP phone, I run into a nned to register the same extension on multiple devices, and I always get the recommendation to create more extensions and use hackery on the PBX to make 'em work like they're a single one. That's not good enough. The other protocols we use to communicate (XMPP, POP/IMAP/SMTP, even proprietary ones like AIM and old ones like POTS) are all friendly to multiple connections to the same account. Why's this functionality missing from SIP? There are only a few use cases, but they're huge ones:

- A user has a desk phone but also wants to take and place calls occasionally from a computer or mobile device over cellular data.
Usually, the desk phone will be the only device registered.
- A user wants an extension represented in two or more geographically separate locations, say on a desk phone at home and a desk phone at work
- A house with extensions in several rooms. Right now, the "IP" part of IP telephony usually evaporates inside the home, where SIP gets bridged to POTS. That's great for retrofits, but as fewer people subscribe to landline service, there will come a time when new homes aren't wired for POTS. At the same time, many new homes ARE being wired with Ethernet.

What do you all think about this problem? (If it's already been discussed to death, feel free to lightly whack me over the head and point me to the right thread :).) _______________________________________________
Sip mailing list https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol Use sip-***@cs.columbia.edu for questions on current sip Use ***@ietf.org for new developments on the application of sip
_______________________________________________
Sip mailing list https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-***@cs.columbia.edu for questions on current sip
Use ***@ietf.org for new developments on the application of sip
Dale Worley
2009-10-12 14:09:32 UTC
Permalink
Post by Sidney San Martín
Whenever I use an IP phone, I run into a nned to register the same
extension on multiple devices, and I always get the recommendation to
create more extensions and use hackery on the PBX to make 'em work
like they're a single one. That's not good enough. The other protocols
we use to communicate (XMPP, POP/IMAP/SMTP, even proprietary ones like
AIM and old ones like POTS) are all friendly to multiple connections
to the same account. Why's this functionality missing from SIP? There
Multiple registrations is a functionality that was built into SIP from
the beginning. Many, many users of sipXecs have been using it for many
years and we have never seen a fundamental problem with it. It is not
clear to me who would recommend to you that multiple registration does
not work in SIP. Is it possible that you are confusing SIP with other
voice-over-IP protocols, some of which do not support multiple
registrations well?

If you have tried to use multiple registrations and they have not
worked, please tell us about your experiences in detail. I'm sure the
problem can be corrected.

Dale


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This list is for NEW development of the core SIP Protocol
Use sip-***@cs.columbia.edu for questions on current sip
Use sipping@
Dale Worley
2009-10-12 15:44:08 UTC
Permalink
Post by Dale Worley
Multiple registrations is a functionality that was built into SIP from
the beginning. Many, many users of sipXecs have been using it for many
years and we have never seen a fundamental problem with it. It is not
clear to me who would recommend to you that multiple registration does
not work in SIP. Is it possible that you are confusing SIP with other
voice-over-IP protocols, some of which do not support multiple
registrations well?
Sorry about that message, I mistook which mailing list I received it
via. However, the above description is valid regarding SIP.
Post by Dale Worley
If you have tried to use multiple registrations and they have not
worked, please tell us about your experiences in detail. I'm sure the
problem can be corrected.
If you have trouble with the sipXecs system, please write to the
sipx-users mailing list (@list.sipfoundry.org). If you have trouble
with other SIP systems, you can write to sip-implementors
(@lists.cs.columbia.edu).

Dale


_______________________________________________
Sip mailing list https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-***@cs.columbia.edu for questions on current sip
Use ***@ietf.org for new developments on the application of sip
Scott Lawrence
2009-10-12 15:51:53 UTC
Permalink
Post by Sidney San Martín
Disclaimer: I'm not involved in the SIP community and not very
familiar with its implementation or history.
Whenever I use an IP phone, I run into a nned to register the same
extension on multiple devices, and I always get the recommendation to
create more extensions and use hackery on the PBX to make 'em work
like they're a single one. That's not good enough.
Then you should find other phones and/or other PBXs. Multiple
registrations should just work with no hackery required.


_______________________________________________
Sip mailing list https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-***@cs.columbia.edu for questions on current sip
Use ***@ietf.org for new developments on the appl

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