[asterisk-dev] STUN support in chan_sip revisited

[Simon Perreault]

On 2010-08-09 04:38, Klaus Darilion wrote:
> 
> Am 08.08.2010 21:16, schrieb Simon Perreault:
>> - What's the problem with using a small expiry parameter value in the
>> register line?
> 
> Some providers reject too small Expires values.

 The Expires header sent by the client is only a suggestion. It's up to
the registrar to decide. But that's of no consequence.

> Thus Asterisk would need 
> a feature to send REGISTERs with the required high Expires header, but 
> reregisters much earlier although the registration has not expired.

Yes!

And note that this is 100% compliant with RFC 3261. The only purpose of
the Expires header returned by the registrar is to inform the client of
the registration's life-time. The client is free to re-register (or not)
at any moment.

The right value for the Expires header to be sent to the registrar could
be determined automatically from the Min-Expires header that the
registrar sends us when it rejects the initial REGISTER with a 423
(Interval Too Brief). Asterisk would send a new REGISTER request with
this value but the actual re-registration interval would be the one
configured statically in sip.conf. Would that work?

Simon
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