[Asterisk-Users] Remote employees using Polycom 501 lose ability to receive incoming calls after few minutes.

[Dr. Michael J. Chudobiak]

Von L. wrote:
> plugged in. They work immediately after being plugged in, but they lose
> the ability shortly thereafter. They can always make outbound calls, but
> only to real phone numbers, not extensions.
> 
> They each have NAT routers, and I have triple checked that they have
> opened/forwarded the correct ports, basically 5060-30000 UDP. Once they


See the "NAT Issues" section at http://www.voip-info.org/wiki/view/IAX.
(The page is for IAX2, but the NAT issues are relevant for UDP SIP ports
too).

Basically, some NAT routers "forget" UDP mappings after a VERY short
time (like 30 seconds). Took me a while to figure that out.


- Mike