[Asterisk-Dev] [BUG?] chan_sip, RFC 3261 and multiple UACs registering for one account

[Tim Robbins]

> -----Original Message-----
> From: asterisk-dev-bounces at lists.digium.com 
> [mailto:asterisk-dev-bounces at lists.digium.com] On Behalf Of 
> Kevin P. Fleming
> Sent: Tuesday, 30 August 2005 3:56 AM
> To: Asterisk Developers Mailing List
> Subject: Re: [Asterisk-Dev] [BUG?] chan_sip,RFC 3261 and 
> multiple UACs registering for one account
> 
> Hartwig Deneke wrote:
> 
> > I respect the decision of Asterisk developers to  support only one 
> > device per channel. However, from a usability perspective, it seems 
> > terrible to let the REGISTER requests of two devices succeed 
> > successfully, making both devices think they are in 
> REGISTERed state, 
> > while this is actually not the case. It would be far better to fail 
> > the second registration then.
> 
> If you can give us an absolutely 100% guaranteed way to know 
> that the second REGISTER is not coming from the same device 
> (which has just moved), then we can reject the second one.
> 
> However, I already know the answer to that question: you 
> can't. There is no way to conclusively prove that a REGISTER 
> is not coming from the same device that already registered with us.

This is one of the problems that GRUU (draft-ietf-sip-gruu-03) solves. If
the +sip.instance parameter of the Contact address is the same, it's a
second registration from the same device.

--
Tim Robbins
Teragen International Pty. Ltd.