asterisk users - May 2006 - Using qualify=yes guarantees failure on iax2 behind NAT (was: RE: Using frequent keepalives to eliminate needforNAT port forwarding?)

> So now I have a new question (besides my original,
> about how to ensure that asterisk _always_ answers the
> phone): why would enabling "qualify" cause an
> immediate and consistent failure to ever answer
> incoming external phone calls?
Because the firmware on your NAT router has an unconditional timeout on
NAT entries, so the qualify = yes can not keep the NAT open.

Have you tried upgrading your router firmware and or trying a different
router?

We use qualify and nat exclusively with SIP. Not IAX, so if there is an
IAX related unique issue I would not have any experience.

We have hundreds of SIP devices behind NAT routers with no NAT traversal
other than qualify and nat = yes and the only problems we have ever had
have been related to old and/or junky routers, most of which can be
fixed by upgrading the firmware or replacing the router with a basic
consumer router from a reputable manufacturer.

The endpoints are all of the Linksys/Sipura variety or Polycom phones,
none of the NAT traversal features in the device are enabled.

I should also add that our asterisk servers are NOT behind any NAT, only
the SIP UAs are.