[asterisk-users] Understanding NAT Traversal

[Brian Candler]

On Tue, Oct 10, 2006 at 05:03:30PM -0400, hugolivude wrote:
>    Similarly, why do we need a timeout on a SIP registration?  Does this
>    work the same way as a "heartbeat" enabling disconnected UA to be
>    unregistered?

Yes, that's the purpose: so that if you unplug a SIP phone without giving it
a chance to unregister itself, it will eventually be unregistered due to the
timeout.

(Additionally, some half-baked SIP NAT solutions require you to set a
ludicrously short registration timeout, e.g. 20 seconds, just to keep UDP
state open on the firewall)

Regards,

Brian.