User's Manual
GXP2130/GXP2140/GXP2160/GXP2170/GXP2135   
ADMINISTRATION GUIDE 
Page 38 of 85 
use the Callee or proxy server as the refresher. The default setting is "Omit". 
UAS Specify Refresher 
As a Callee, select UAC to use caller or proxy server as the refresher; or select 
UAS to use the phone as the refresher. The default setting is "UAC". 
Force INVITE 
The Session Timer can be refreshed using the INVITE method or the UPDATE 
method. Select "Yes" to use the INVITE method to refresh the session timer. 
The default setting is "No". 
Account x  SIP Settings  Security Settings 
Check Domain 
Certificates 
Choose whether the domain certificates will be checked or not when TLS/TCP 
is used for SIP Transport. The default setting is "No". 
Validate Certificate Chain 
Validate certification chain when TCP/TLS is configured. The default setting is 
“No”. 
Validate Incoming 
Messages 
Choose whether the incoming messages will be validated or not. The default 
setting is "No". 
Check SIP User ID for 
incoming INVITE 
If set to "Yes", SIP User ID will be checked in the Request URI of the incoming 
INVITE. If it doesn't match the phone's SIP User ID, the call will be rejected. 
The default setting is "No". 
Accept Incoming SIP 
from Proxy Only 
When set to "Yes", the SIP address of the Request URL in the incoming SIP 
message will  be checked.  If it doesn't match the SIP  server address of  the 
account, the call will be rejected. The default setting is "No". 
Authenticate Incoming 
INVITE 
If set to "Yes", the phone will challenge the incoming INVITE for authentication 
with SIP 401 Unauthorized response. The default setting is "No". 
Account x  Audio Settings 
Send DTMF 
This parameter specifies the mechanism to transmit DTMF digits. There are 3 
supported  modes:  in  audio  which  means  DTMF  is  combined  in  the  audio 
signal (not very reliable with low-bit-rate codecs), via RTP (RFC2833), or via 
SIP INFO. 
•  In  audio,  which  means  DTMF  is  combined  in  the  audio  signal  (not  very 
reliable with low-bit-rate codecs);                                                                                                                       
• RFC2833, which means to specify DTMF with RTP packet. Users could know 
the packet is DTMF in the RTP header as well as the type of DTMF;                                                                                                                 
• SIP INFO, which use SIP info to carry DTMF. The defect of this mode is that 
it's easily to cause desynchronized of DTMF and media packet for the reason 
the  SIP  and  RTP  are  transmitted  respectively.  The  default  setting  is 
"RFC2833". 
DTMF Payload Type 
This parameter  sets the payload type for DTMF using RFC2833.  Default is 
101. The valid range is from 96 to 127. 










