(12-04-2014 12:55 AM)miclan Wrote: Both phones are inside a LAN.
The SIP-PBX is in an external WAN.
Both phones always work perfect with outgoing calls.
The problem occurs with incoming calls:
Just after booted, both phones are reachable for incoming calls, sometimes.
But most of the time the phones cannot be connected from the external PBX.
Interresting:
Two different softphones from other venders in the same LAN work perfectly well for incoming calls with that external PBX.
The PBX vendor (Starface) analyzed the PBX logs and says:
The softphones might have a relative short keep alive signal period which keeps the way through the NAT router.
But the Yealink phones seem to have a very long keep alive every 60 minutes or so and it might be, that the NAT-router does not hold it's NAT-tables for such a long period and therefore starts to deny before the next keep alive signal.
Question:
Is it possible to shorten the keep alive signal period at the T46G and T48G?
Or do you have another suggestion?
The defaults of the Yealink phones is to have keep-alive, and send at 30 second internals:
#Enable or disable the NAT keep-alive; 0-Disabled, 1-Default (default)2-Option, 3-Notify;
account.1.nat.udp_update_enable = 1
#Specify the keep-alive interval (in seconds), the default value is 30.
account.1.nat.udp_update_time = 30
You can also access these settings via the web interface, under Account\Advanced.
This works well for us, but we also have keep-alive packets sent inbound to the phone via asterisk qualify. Your PBX provider should be able to enable this(or a similar functionality) to assist in keeping the NAT pinhole open through your router's firewall.
Alternatively, using the TCP transport type if available will generally resolve NAT pinhole issues, as the default connection close timers are much longer for idle TCP connections than for UDP, which can be as low as 30 seconds on some routers I've seen.