In many voice telephone networks, anonymous call rejection (ACR) is a

calling feature A vertical service code (VSC) is a sequence of digits and the signals star (*) and number sign (#) dialed on a telephone keypad or rotary dial to enable or disable certain telephone service features. Some vertical service codes require dialing of ...

implemented in software on the network that automatically screens out calls from callers who have blocked their

caller ID Caller identification (Caller ID) is a telephone service, available in analog and digital telephone systems, including voice over IP (VoIP), that transmits a caller's telephone number to the called party's telephone equipment when the call is ...

information. The caller usually hears a voice message explaining that their call cannot be connected unless they display their number. Or, some networks allow users to forward anonymous calls directly to voicemail. The service, together with

Caller ID Caller identification (Caller ID) is a telephone service, available in analog and digital telephone systems, including voice over IP (VoIP), that transmits a caller's telephone number to the called party's telephone equipment when the call is ...

, became possible with the introduction of digital switching technologies to

landline telephone A landline (land line, land-line, main line, home phone, fixed-line, and wireline) is a telephone connection that uses metal wires or optical fiber telephone line for transmission, as distinguished from a mobile cellular network, which uses ...

services, which became widespread in many countries throughout the 1980s and 1990s. In a classic digital

PSTN The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local teleph ...

network it could be implemented directly in software running on local switching systems or, more commonly, as part of a suite of facilities supported by an additional layer known as the Intelligent Network (IN). This allowed more advanced, software based, services to be rolled out in public telephone networks using dedicated intelligent nodes, operating in conjunction with, but independently of switching systems. As voice telephony continues evolve ACR remains available on modern and can be relatively easily implemented in

VoIP Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet t ...

based services and is also available on some mobile networks. Some providers may include this service as standard, while others may require a subscription and others still do not offer it at all. This may be for technical reasons, but as the service is supported by most vendors, it is more likely a commercial decision. Mobile networks often do not offer the service, as handsets (particularly

smartphones A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, which ...

) have sufficient computing power to offer advanced call filtering and logging options using their own software. They are often even able to use apps to consult databases to provide advanced information about calls, even identifying potential scams, fraudsters and nuisance calls. Even the most basic mobile handsets usually offer the ability to mute or reject anonymous calls. In this case, software on the handset itself screens the calls, without relying on network switches. These features are activated though the phone’s menus. On more modern landline services, particularly those using VoIP, ACR is sometimes activated and deactivated using a Web interface, rather than by dialling codes. On traditional landlines in the

North American Numbering Plan The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the international callin ...

the feature is enabled with the

vertical service code A vertical service code (VSC) is a sequence of digits and the signals star (*) and number sign (#) dialed on a telephone keypad or rotary dial to enable or disable certain telephone service features. Some vertical service codes require dialing of ...

, and disabled with .. In

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

various codes are in use, including:

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

Virgin Media Virgin Media is a British telecommunications company which provides telephone, Cable television, television and Internet access, internet services in the United Kingdom. Its headquarters are at Green Park in Reading, Berkshire, Reading, Engla ...

Activate: Deactivate:

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

BT Activate: Deactivate: Check Status:

Service usage messages

"Your anonymous call rejection service is now on. Callers who block their number will get a recording saying you do not accept blocked calls." "Your anonymous call rejection service is now off. Callers who block their number can now reach you." “The person you are trying to reach does not wish to accept calls from callers who withhold their number. Please try your call again, without withholding your number.” (Recorded message, as heard in Ireland.)

References

{{Reflist

External links

Anonymous call rejection recordings archive
Caller ID Calling features Telephone service enhanced features

Service usage messages

See also

References

External links