User Guide
Grandstream Networks, Inc.  GXP User Manual  Page 38 of 44 
       Firmware 1.2.5.3     Last Updated: 03/2011 
Authenticate Password 
SIP service subscriber’s account password for GXP to register to (SIP) servers of 
ITSP. 
Name 
SIP service subscriber’s name that is used for Caller ID display. 
Use DNS SRV: 
Default is No. If set to “Yes”, the client will use DNS SRV to look up server. 
User ID is Phone 
Number 
If the phone has an assigned PSTN telephone number, this field should be set to 
“Yes”. Otherwise, set it to “No”. If “Yes” is set, a “user=phone” parameter will be 
attached to the “From” header in SIP request 
SIP Registration 
This parameter controls sending REGISTER messages to the proxy server. The 
default setting is “Yes”.  
Un-register on Reboot 
Default is “No”. If set to “Yes”, the SIP user’s registration information will be 
cleared from the server when the phone reboots. 
SIP Instance ID 
Default is set “No.” If set to Yes it will be enabled and will add reg-ID and Instance 
ID on contact header in the REGISTER messages. This feature is mainly 
provided for servers that don't support SIP Instance ID feature, but will still allow 
phones to register.  
Register Expiration 
This parameter allows user to specify the time frequency (in minutes) that GXP 
refreshes its registration with the specified registrar. The default interval is 60 
minutes. The maximum interval is 65,535 minutes (about 45 days). 
Local SIP Port 
This parameter defines the local SIP port used to listen and transmit. The default 
value for Account 1 is 5060. It is 5062, 5064, 5066 for Account 2, Account 3 and 
Account 4 respectively. 
SIP Registration Failure 
Retry Wait Time 
Retry registration if the process failed. Default is 20 seconds. 
SIP T1 Timeout 
RFC 3261 SIP T1 timer. Default is 1 second. 
SIP T2 Interval 
RFC 3261 SIP T2 timer. Default is 0.5 seconds. 
SIP Transport 
Choose SIP Transport between UDP and TCP. Default is UDP. 
Use RFC3581 
Symmetric Routing 
Default No. When selected the phone will follow the routing procedures specified 
in RFC3581. 
NAT Traversal (STUN) 
This parameter activates the NAT traversal mechanism. If activated (by choosing 
“Yes”) and a STUN server is also specified, the phone performs according to the 
STUN client specification. Using this mode, the embedded STUN client detects if 
and what type of NAT/Firewall configuration is used. If the detected NAT is a Full 
Cone, Restricted Cone, or a Port-Restricted Cone, the phone will use its mapped 
public IP address and port in all of its SIP and SDP messages. If the NAT 
Traversal field is set to “Yes” with no specified STUN server, the GXP will 
periodically (every 20 seconds or so) send a blank UDP packet (with no payload 
data) to the SIP server to keep the “hole” on the NAT open. 
SUBSCRIBE for MWI: 
Default is No. When set to “Yes” a SUBSCRIBE for Message Waiting Indication 
will be sent periodically. 










