Yealink SIP-T2XP Administrator's Manual page 195

Details of the Configuration Parameter:
features.normal_refuse_code
Description:
Configures a return code and reason of SIP response messages when the IP phone
rejects an incoming call. A specific reason is displayed on the caller's phone LCD
screen.
404-No Found
480-Temporarily Unavailable
486-Busy Here
If it is set to 486 (Busy Here), the caller's phone LCD screen will display the message
"Busy Here" when the callee rejects the incoming call.
Web User Interface:
Features->General Information->Return Code When Refuse
Phone User Interface:
None
To specify the return code and the reason when refusing a call via web user interface:
1. Click on Features->General Information.
2. Select the desired value from the pull-down list of Return Code When Refuse.
3. Click Confirm to accept the change.
Parameter
Configuring Basic Features
Permitted Values Default
404, 480 or 486 486
177