Hello all,

Looking for some help.

Quick background. We have a Virgin Media Router with a rotatable /29 from here to the Draytek. We have the Draytek going into a switch and the PBX connections to this switch. ( all this works fine).

The issue is when calls are idle ( no calls in or out over a 48 period) we cant seem to get calls in IN ( we are getting 401 send back from the SIP carrier). To fix this we make a call OUT and this issues goes away.

We think we have a NAT timer issue on Draytek or double NAT issues.

Has any seen this before?

Thanks

That's the DrayTek router's UDP session timeout value ending your idle SIP sessions.

To fix that, use the "portmaptime" command in the router's CLI.

"portmaptime -l" - view the current settings.

"portmaptime -u 86400" - increase the UDP session timeout to 24 hours (86400 seconds).

That should fix it

Thanks will give that a go!