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.
Terminology 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.
Keypad codes North America
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: The Sprint Nextel cellphone company uses these:
As of Jan 2012, Sprint charges 20 cents per minute for unconditional call forwarding,
conditional call forwarding is included however.
Some carriers use *71 for conditional forwarding although this is not standard.
Sometimes, to deactivate a call forwarding, *720 will work on cellphones.
Europe Most EU fixed-line carriers use the following
codes based on CEPT and ETSI standards developed in the 1970s on both POTS and ISDN lines:
The general syntax for all European service codes always follows the pattern below:
Mobile phones For GSM/3GSM phones, the GSM standard defines
the following forwarding codes.
These were developed by ETSI and are based on standard European diversion codes and are
similar to those used on most landlines in the EU:
If the prefix to the forwarding command is "**", then the phone number in that command
is registered in the network.
If after that the forwarding is deactivated using a command with a single "#", then later
it will be possible to re-activate this forwarding again with a simple "*" command without a
phone number in it.
The forwarding will be re-activated to the number registered in the network.
For example, if one uses the out-of-reach code in a forwarding command:
**62*7035551212# and after that one deactivates the forwarding:
#62# then later it will be possible to re-activate
the out-of-reach forwarding without specifying a number:
*62# After the above command, all calls made to
the phone, while it is out of reach, will be forwarded to 7035551212.
It is possible to activate the feature to a number other than the registered number,
whilst still retaining the registered number for later use.
For example, issuing the command: *62*7185551212#
will result in calls being forwarded to 7185551212.
However, if later a command is issued: *62#
then the calls will again be forwarded to the registered number 7035551212.
Additionally, in GSM networks, such as T-Mobile and AT&T Mobility in USA, and all mobile networks
in EU, it is possible to set the number of seconds the phone will ring before forwarding.
This is specified by inserting "*SC*XX" prior to the final "#" of the forwarding command,
where "SC" is a service type code, and "XX" is the number of seconds in increments of
5 seconds.
If "SC" is omitted then by default all service types will be forwarded.
For example, forwarding on no-answer can be set with:
*61*[phone number]**[seconds]# In some networks there may be a limit of not
more than 30 seconds before forwarding.
Uses Diverting calls can increase one's availability
to a caller.
The main alternative is an answering machine or voicemail, but some callers do not wish
to leave a recorded message, suspecting that the party will delay returning their messages.
A caller at a telephone booth may be unable to receive the call if a recorded message
is returned.
Some businesses find that the human touch can improve contact, thus sales, but traditional
wired answering services are expensive, so they have their calls forwarded to a call
center, so the client can reach an operator instead of an answering machine or voice mail.
Often, a suburb of a large city is a toll call from many suburban exchanges on the opposite
side of the same city, even though all of these suburbs are a local call to the city
centre.
A business located in such a suburb may therefore benefit from obtaining a downtown number as
an "extender", to be permanently forwarded to their geographic suburban number.
Where unlimited local calls are flat-rated and long-distance incurs high per-minute charges,
the downtown number's wider local calling area represents a commercial advantage.
Markham is long-distance to Mississauga . A Markham business with a forwarded area code
416 Toronto number could receive calls from Malton airport in Mississauga without incurring
long-distance charges.
Some services offer international call forwarding by allocating for the customer a local virtual
phone number which is forwarded to any other international destination.
As a means to obtain an inbound number from another town or region for business use, call
forwarding schemes tend to be far less expensive than foreign exchange lines but more costly
than using voice over IP to obtain a local number in the chosen city.
See also Follow-me
Hunting Remote call forwarding
Notes
External links Call Forwarding User manual, Bell Canada