Every incoming call can be rejected by the user via the Left Soft Key under the display "Reject"
The device will send an "SIP 603 decline" response message.
If required, the response can be changed via auto-provisioning to:
486 Busy
603 Decline
603 = 603 Decline (Default)
486 = 486 Busy
Example:
<param name="SipProvider.0.DeclineResponse" value="603"/>