Robert K.
How to configure and cancel call forwarding using keypad codes on an Aastra 6755 phone?
To forward to an internal extension, dial 2 1 (Immediate), 2 2 (No answer), or 2 3 (Busy) followed by the extension number. To forward to voicemail, dial 2 5 (Immediate), 2 6 (No answer), or 2 7 (Busy). To cancel all forwardings, dial # 2 0.