User manual

8820IP Phone User Manual_ SIP (V1.44)
28
please select an item from dropdown list.
n disable: Select this item when the sip proxy server and IP phone in
the same LAN, or the sip proxy system supports the IP phone working
behind the LAN.
n enable: When the system does not support IP phone working behind
the LAN, please select this item to search public IP address of the
NAT device. With this item selected, “nat addr” field will be activated.
Besides, port mapping (port forwarding) needs to be properly set up
on NAT device.
n stun: Select this item with Stun server used according to requirement
of system. With this item selected, nat addr field is activated.
● nat addr: When “nat traversal” is set to “enable”, please put the domain
name of the servers ( These web server helps to find out the public IP of
the NAT device) into “nat addr”, such as www.whatismyip.com.
When “nat traversal” is set to “stun”, please put the URI of the stun server
into “nat addr”, in the format as “domain name/IP address : service port”.
The default service port for stun is 3478.
● nat ttl: When IP phone sit behind a NAT device, it will send packets to
server every “nat ttl” seconds to keep the port mapping on the NAT