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Re: [Sip] Dual registration without Outbound





Iñaki Baz Castillo wrote:
El Miércoles, 8 de Octubre de 2008, Paul Kyzivat escribió:
Iñaki,

What you describe is perfectly fine, and is in fact the reasonable thing
to do. You have distinct AORs corresponding to the two numbers, and a
separate contact for each.

What I was asking about was creating multiple Contact addresses for the
*same* AOR.

Perpahs I didn't explain correctly:

I mean that UA (with name "a at doman.com") sends two REGISTER for the same AoR:

1)
REGISTER sip:server
From: sip:a at domain.com
To: sip:a at domain.com
Contact: sip:+34111111 at my_ip

1)
REGISTER sip:server
From: sip:a at domain.com
To: sip:a at domain.com
Contact: sip:+34222222 at my_ip


When the proxy receives a call with RURI = +34111111, it ask the location sevice which returns "a at domain.com". But the proxy, instead fo calling both locations in parallel (or sequentially), it just calls the location with the Contact username matching the incoming RURI (+34111111).

Not sure if it's a good idea.

Its certainly not an idea that appeals to me.

It requires an entirely non-standard routing algorithm within the proxy, selecting contact URI from among the available candidates in a very weird way.

Its an axiom of sip that UAs may choose their contact addresses as they wish. The encoding of any semantic information into that address is the business of the UA and not for any other server to second guess.

In your example, the same proxy is responsible for the following AORs:
- tel:+34111111
- tel:+34222222
- sip:a at domain.com

and probably:

- sip:+34111111 at domain.com
- sip:+34222222 at domain.com

Rather than have the UA register for a at domain.com and have the proxy do a weird mapping based on registered contact addresses, its much more straightforward to have the UA register as follows:

REGISTER sip:domain.com
From: sip:+34111111 at domain.com
To: sip:+34111111 at domain.com
Contact: sip:+34111111 at my_ip

REGISTER sip:domain.com
From: sip:+34222222 at domain.com
To: sip:+34222222 at domain.com
Contact: sip:+34222222 at my_ip

(Its required to use the sip form of the AOR rather than the tel form. Can't have a tel as the To of a REGISTER.)

	Thanks,
	Paul

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