Posted: Sun Apr 20, 2003 9:03 pm Post subject: [Asterisk-Dev] Registrations SHOULD use same Call-ID. Packe
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I was investigating a problem where Packet8 didn't always send me my
incoming calls. Making incoming calls, occasionally
I'd hear ringback but Packet8 wouldn't send Asterisk an INVITE.
Two things were needed to fix. Firstly - Packet8 expires
registrations after 30 seconds (!), but actually seems to want to see
REGISTER even more often than that. The DTA310 sends a REGISTER every
15 seconds.
So I added a define in sip_chan to tweak the amount of "guard time" *
allows. I've set it to 15 seconds in the patch.
I also wrote to the Packet8 guys to find out if the expiry really
needs to be so brutally short!
Secondly: Asterisk uses a different Call-ID for each registration.
RFC3261, section 10.2 (Constructing the REGISTER Request) says:
Call-ID: All registrations from a UAC SHOULD use the same Call-ID
header field value for registrations sent to a particular
registrar.
If the same client were to use different Call-ID values, a
registrar could not detect whether a delayed REGISTER request
might have arrived out of order.
OK - so its a SHOULD not a MUST. And I can't say I understand the
reasoning. But I adjusted chan_sip to keep the same Call-ID for all
REGISTERs to a particular registry and that fixed my remaining
problems with incoming calls nicely.
In any case, it improves our compliance with the RFC, and its a very
tiny patch (half the code seemed to be there already, anyway).
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