Call forwarding (or call diverting), in telephony, is a feature on some telephone networks that allow an incoming call to a called party which would be otherwise unavailable to be redirected to a mobile telephone or other telephone number where the desired called party is situated. Usually, the forwarded line rings once, to remind anyone there that calls are being redirected.

Notice that the fee charging structure for a calling party to place a call to the called party which has their number forwarded can be subtle: if the called party has forwarded their number to a mobile telephone, the caller could incur higher rates due to the subsequent use of the mobile telephone network. However, the line which is being forwarded usually incurs all related charges, including long distance.

Special types of call forwarding can be activated only if the line is busy, or if there is no answer, or even only for calls from selected numbers. In North America, the NANP uses the following vertical service codes to control call forwarding:

• forward all calls: *72, activation; *73, deactivation
• on busy or no answer: *68, activation; *88, deactivation
• from select callers: *63, activation; *83, deactivation
• on ISDN: *56, change forward-to number

Customer-programmable features (where available):

• busy line: *90, activation; *91, deactivation; *40, change number
• no answer: *92, activation; *93, deactivation; *42, change number