It configures the IP address or domain
name of the STUN server for account X.
The default value is blank.
It configures the type of keep-alive
packets sent by the phone to the NAT
device to keep the communication port
open so that NAT can continue to
function for account X.
0-Dsiabled
1-Default: the phone sends UDP
packets to the server.
2-Option: the phone sends SIP OPTION