User's Manual
FIRMWARE VERSION 1.0.0.2     GXW42XX USER MANUAL      Page 45 of 52 
Symmetric RTP  Default is No. When set to Yes the device will change the destination to send RTP 
packets to the source IP address and port of the inbound RTP packet last received by
the device. 
Fax Mode 
T.38 (Auto Detect) FoIP by default, or Pass-Through (must use codec PCMU/PCMA) 
Fax Tone Detection 
Mode 
Default is Callee. This decides whether Caller or Callee sends out the re-INVITE for 
T.38 or Fax Pass Through. 
Jitter Buffer Type 
Select either Fixed or Adaptive based on network conditions. 
Jitter Buffer Length 
Select Low, Medium or High based on network conditions. 
•  High (initial 200ms, min 40ms, max 600ms) Note: not all vocoders can meet the 
high requirement 
•  Medium (initial 100ms, min 20ms, max 200ms) 
•  Low (initial 50ms, min 10ms, max 100ms) 
SRTP Mode  Default is Disabled. Other options are Enabled but not forced, and Enabled and 
forced. 
It uses SDP Security Description to exchange key. Please refer 
SDES: http://www.apps.ietf.org/rfc/rfc4568.html 
SRTP: http://www.apps.ietf.org/rfc/rfc3711.html 
SLIC Setting 
Depends on standard phone type (and location) 
Caller ID Scheme 
Select the value according to the local Telco standard where the GXW42XX is installed. 
Please refer to the pull down list to select. 
Polarity Reversal  Default is No. If set to “Yes”, polarity will be reversed upon call establishment and 
termination. 
Loop Current 
Disconnect 
Set to Yes if the traditional PBX you are using with GXW42XX uses this method for 
signaling call termination. Default is No. 
Loop Current 
Disconnect duration 
Default is 200. In 100 - 1 0000 milliseconds range. 
Hook Flash timing 
Time period when the cradle is pressed (Hook Flash) to simulate FLASH. To prevent 
unwanted activation of the Flash/Hold and automatic phone ring-back, adjust this time 
value. 
On Hook Timing 
On-hook timing is the minimum time for an on-hook event to be validated. 










