Call waiting is a

telephone A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into e ...

service where a subscriber can accept a second incoming

telephone call A telephone call is a connection over a telephone network A telephone network is a telecommunications network that connects telephones, which allows telephone calls between two or more parties, as well as newer features such as fax and interne ...

by placing an in-progress call

on hold In telephony, a call may be placed on hold, in which case the connection is not terminated but no verbal communication is possible until the call is removed from hold by the same or another extension on the key telephone system. Music on hold or ...

—and may also switch between calls. With some providers it can be combined with additional features such as conferencing,

call forwarding Call forwarding, or call diversion, is a telephony feature of all telephone switching systems which redirects a telephone call to another destination, which may be, for example, a mobile or another telephone number where the desired called party is ...

, and

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 i ...

. Call waiting is intended to alleviate the need to have more than one telephone line or number for voice communications.

History

Call waiting was introduced to North America in the early 1970s when the first generation of electronic switch machines built by

Western Electric The Western Electric Company was an American electrical engineering and manufacturing company officially founded in 1869. A wholly owned subsidiary of American Telephone & Telegraph for most of its lifespan, it served as the primary equipment ma ...

, Electronic Signaling System 1 started to replace older mechanical equipment in the old

Bell System The Bell System was a system of telecommunication companies, led by the Bell Telephone Company and later by the American Telephone and Telegraph Company (AT&T), that dominated the telephone services industry in North America for over one hundr ...

local telephone companies. At first, some smaller municipalities were able to offer customers call waiting only on a specific phone exchange (e.g., phone customers in Trenton,

Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...

initially had to have a phone number starting with 671 to have call waiting, since 671 was at that time the only exchange in that area served by one of the new ESS switches), but as demand for it became more widespread, it eventually became available on all phone exchanges as the older equipment was phased out. In Europe, call waiting was also introduced in the 1970s with the introduction of the first digital switching systems such as the

Ericsson (lit. "Telephone Stock Company of LM Ericsson"), commonly known as Ericsson, is a Swedish multinational networking and telecommunications company headquartered in Stockholm. The company sells infrastructure, software, and services in informa ...

AXE An axe ( sometimes ax in American English; see spelling differences) is an implement that has been used for millennia to shape, split and cut wood, to harvest timber, as a weapon, and as a ceremonial or heraldic symbol. The axe has ma ...

Alcatel Alcatel may refer to: * Alcatel, a former French telecommunications equipment company, which became Alcatel-Lucent and is now part of Nokia * Alcatel Mobile, a brand of mobile phones, tablets and wearables, formerly a joint venture between Alcatel ...

E10 and System 12. It was also available on some

crossbar exchanges, such as the ARE11 which, while electromechanical, was also computerised. Other digital systems such as the UK's System X also supported the service. Switching systems developed in the 1980s such as the German

Siemens Siemens AG ( ) is a German multinational conglomerate corporation and the largest industrial manufacturing company in Europe headquartered in Munich with branch offices abroad. The principal divisions of the corporation are ''Industry'', '' ...

/ Bosch

EWSD The Elektronisches Wählsystem Digital (EWSD), translated to ''Electronic Digital Switching System'' in English, is a widely installed German telephone exchange system, originally introduced in 1975 by Siemens AG, but discontinued in 2017. EWSD ...

also had call waiting.

Star codes

In North America, the

NANP 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 calling ...

uses the *70

star code A vertical service code (VSC) is a sequence of digits and the signals asterisk, 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 ...

prefix to suspend call waiting for a dialed call. A stutter

dial tone A dial tone is a telephony Signaling (telecommunication), signal sent by a telephone exchange or private branch exchange (PBX) to a terminating device, such as a telephone, when an off-hook condition is detected. It indicates that the exchange is ...

confirms the de-activation. On most European telephone networks, and

GSM The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation ( 2G) digital cellular networks used by mobile devices such ...

UMTS The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the Inte ...

mobile phones, call waiting is activated by dialing the following codes: * To activate: *43# * To deactivate: #43# * To check status: *#43# A voice announcement, tone or a message on your phone's screen will confirm the service status. Call waiting in Europe uses an "R" (recall) button on the phone. This performs a similar function to a North American

hook flash On analog telephone lines with special services, a flash or register-recall signal is used to control functions on the public telephone exchange, PBX or VoIP ATA. The term "register-recall" in Europe refers to sending a discrete signal to alert t ...

button but is much shorter duration, typically 80ms to 100ms, vs. 250ms in North America. In some networks, pressing R toggles between the calls, similar to North America. However, in most countries there are further options: * R1 – Answer the waiting call and hang up on the current call. * R2 – Toggle between the calls. * R3 – Merge the two calls for conference calling. * R0 – Reject call waiting – This will send the call to voice mail or a busy tone.

Type II 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 ...

also works with call waiting.

Line sharing

Since the waiting call uses a

zip tone In telephony, a zip tone (also known as a whisper tone or call waiting tone) is a call-progress tone which indicates a new incoming call is either connecting or waiting depending on the application. Unlike a ringtone, which alerts those near a tel ...

(for example, a 440 Hz beep every ten seconds in North America), call waiting can cause

dial-up Internet access Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telepho ...

connections to terminate, unless the

modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by Modulation#Digital modulati ...

supports the most recent

V.92 V.92 is an ITU-T recommendation, titled ''Enhancements to Recommendation V.90'', that establishes a modem standard allowing near 56 kb/s download and 48 kb/s upload rates. With V.92 PCM is used for both the upstream and downstream connections; prev ...

modem standard. For this reason, call waiting is often disabled on shared

voice The human voice consists of sound made by a human being using the vocal tract, including talking, singing, laughing, crying, screaming, shouting, humming or yelling. The human voice frequency is specifically a part of human sound production in ...

lines used for dial-up modem or fax purposes. However, Call Waiting has no impact on

DSL Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric dig ...

connections.

Call waiting deluxe

Call waiting deluxe is the

Bellcore iconectiv is a supplier of network planning and network management services to telecommunications providers. Known as Bellcore after its establishment in the United States in 1983 as part of the break-up of the Bell System, the company's name ...

(now

Telcordia Technologies iconectiv is a supplier of network planning and network management services to telecommunications providers. Known as Bellcore after its establishment in the United States in 1983 as part of the break-up of the Bell System, the company's name ...

) term for Type II

with Disposition Options. This

CLASS Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

-based POTS-telephone calling feature works by combining the services of call waiting with

but also introduces an "options" feature that, in conjunction with certain screen-based telephones, or other capable equipment, gives a telephone user the option to: * Switch: Place the current call on hold to take the second call (not a new feature) * Hang-up: Disconnect the current call and take the second call * Please Hold: Send the caller either a custom or telephone-company-generated voice message asking the caller to hold * Forward to Voice Mail: Send the incoming caller to the recipient’s

voice mail A voicemail system (also known as voice message or voice bank) is a computer-based system that allows users and subscribers to exchange personal voice messages; to select and deliver voice information; and to process transactions relating to ind ...

service. * Join: Add the incoming caller to the existing conversation.

External links

Call waiting user manual
an
Call waiting product specifications
from Bell Canada

References