Call forwarding

Call forwarding, or call diversion, is a telephony feature of some telephone switching systems which redirects a telephone call to another destination, which may be, for example, a mobile telephone, voicemail box or another telephone number where the desired called party is available. Call forwarding was invented by Ernest J. Bonanno. In North America, the forwarded line usually rings once to remind the customer using call forwarding that the call is being redirected. More consistently, the forwarded line indicates its condition by stutter dial tone. Call forwarding typically can redirect incoming calls to any other domestic telephone number, but the owner of the forwarded line must pay any toll charges for forwarded calls. Call forwarding is often enabled by dialing *72 followed by the telephone number to which calls should be forwarded. Once someone answers, call forwarding is in effect. If no one answers or the line is busy, the dialing sequence must be repeated to effect call forwarding. Call forwarding is disabled by dialing *73. This feature requires a subscription from the telephone company. Also available in some areas is Remote Access to call forwarding, which permit the control over call forwarding from telephones other than the subscriber's telephone. VOIP and cable telephone systems also often allow call forwarding to be set up and directed via their web portals.

In Europe, most networks indicate that unconditional call forwarding is active with a special dial tone. When the phone is picked up it is immediately apparent that calls are being forwarded.

The ISDN Diversion supplementary services standards document uses "diversion" as a general term to encompass specific features including "Call Forwarding Busy", "Call Forwarding No Reply" and "Call Deflection".

The terms call forwarding and call diversion are both used to refer to any feature that allows a call to be routed to a third party, and the terms are generally interchangeable.

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 generally uses the following vertical service codes to control call forwarding:

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