Grandstream Networks GXP2130 Administration Manual page 34

NAT Traversal
Proxy-Require
Account x -> SIP Settings -> Basic Settings
TEL URI
SIP Registration
Unregister On Reboot
GXP2130/GXP2140/GXP2160
FIRMWARE VERSION 1.0.4.16
the server by DNS SRV, the user may select "SRV" or "NATPTR/SRV".
If "Use Configured IP" is selected, please fill in the three fields below:

Primary IP:

Backup IP 1;

Backup IP 2.
If SIP server is configured as domain name, phone will not send DNS query,
but use "Primary IP" or "Backup IP x" to send SIP message if at least one of
them are not empty. Phone will try to use "Primary IP" first. After 3 tries
without any response, it will switch to "Backup IP x", and then it will switch
back to "Primary IP" after 3 re-tries.
If SIP server is already an IP address, phone will use it directly even "User
Configured IP" is selected.
This parameter configures whether the NAT traversal mechanism is
activated. Users could select the mechanism from No, STUN, Keep-alive,
UPnP, Auto or VPN. The default setting is "No".
If set to "STUN" and STUN server is configured, the phone will route
according to the STUN server. If NAT type is Full Cone, Restricted Cone or
Port-Restricted Cone, the phone will try to use public IP addresses and port
number in all the SIP&SDP messages. The phone will send empty SDP
packet to the SIP server periodically to keep the NAT port open if it is
configured to be "Keep-alive". Configure this to be "No" if an outbound proxy
is used. "STUN" cannot be used if the detected NAT is symmetric NAT. Set
this to "VPN" if OpenVPN is used.
A SIP Extension to notify the SIP server that the phone is behind a
NAT/Firewall. Do not configure this parameter unless this feature is
supported on the SIP server.
If the phone has an assigned PSTN telephone number, this field should be
set to "User=Phone". Then a "User=Phone" parameter will be attached to
the Request-Line and "TO" header in the SIP request to indicate the E.164
number. If set to "Enable", "Tel:" will be used instead of "SIP:" in the SIP
request. The default setting is "Disable".
Selects whether or not the phone will send SIP Register messages to the
proxy/server. The default setting is "Yes".
If set to "Yes", the SIP user's registration information will be cleared when
the phone reboots. The SIP Contact header will contain "*" to notify the
GXP2130/GXP2140/GXP2160
ADMINISTRATION GUIDE
Page 32 of 81