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Re: [reSIProcate-users] Refresh registration as UAC


On 2/11/10 13:14, Feb 11, Scott Godin wrote:
Hi Richard,

When you send the REGISTER you are requesting an expires time.  It
doesn't mean that the server will honor it.  In fact 60 seconds is so
low, I would not be surprised to learn that the registrar you are
using thinks the same and is returning another (higher) value to you
in the 200 response to the registration.

To be clear, that would be in violation of RFC 3261. A registrar can shorten this time, but it is not allowed to lengthen it. Instead, it must return a 423 response, indicating the shortest allowed time. The client is then responsible for resubscribing with this new time. Here's the relevant passage from the standard:

         The registrar MAY choose an expiration less than the requested
         expiration interval.  If and only if the requested expiration
         interval is greater than zero AND smaller than one hour AND
         less than a registrar-configured minimum, the registrar MAY
         reject the registration with a response of 423 (Interval Too
         Brief).  This response MUST contain a Min-Expires header field
         that states the minimum expiration interval the registrar is
         willing to honor.

/a