Yealink provisionning : activate UDP ping if the endpoint is behind nat

In the current configuration, whether the Yealink terminal is behind NAT or not, UDP ping is disabled.

This configuration is only desirable if the IPBX and the set are in the same network (but activating this function in this case has no side effect, apart from the number of UDP packets received by the IPBX plus important).

However, this poses problems closing the SIP port in the NAT table of the router, making the phone unreachable from the point of view of the IPBX, especially if the timer is short (in some firewalls, it is 30 seconds! )

The solution is to modify account. Line_no. Nat.udp_update_enable = 0 and set the value to 1.

It might be interesting in the case of advanced configuration to offer the administrator greater granularity in the choice, thus allowing adaptation to all topologies:

0-Disabled
1-Default (the phone sends the corresponding packets according to the transport protocol)
2-Options (the phone sends SIP OPTIONS packets to the server)
3-Notify (the phone sends SIP NOTIFY packets to the server)

I do not know now, if we have the same issues with other phones !