Message Waiting Indicator
Encyclopedia
A message-waiting indicator (MWI) in telephony
, is a Telcordia Technologies
(formerly Bellcore) term for an FSK
-based telephone
calling feature that illuminates an LED
on select telephones to notify a telephone user of waiting voicemail
messages on most North American public telephone networks and PBXs.
As described in Telcordia Generic Requirements document GR-283-CORE, a Message_Waiting_Indicator (MWI) is a mechanism that informs the subscriber about the status of recorded messages. The subscriber may subscribe to a notification feature that makes use of the status of this MWI.
(CPE) to notify the customer that new messages are waiting. VMWI differs from existing features that use other message indicators, such as audible stuttered dial tone
, in that it activates a visual indicator on the CPE. The visual indicator may be as simple as lighting or flashing a light-emitting diode
(LED), or as advanced as displaying a special message on a liquid-crystal display (LCD).
This technology was introduced in 1995, with the introduction of CLASS-based calling features and ADSI
. It was at one time only compatible with ADSI
-compliant telephones but is now compatible with any customer premises equipment (CPE
) that simply responds visually to visual FSK
.
standalone set-top boxes. Caller ID boxes manufactured after 1998 feature an LED
that blinks green to notify that new calls have been recorded and red to indicate that a subscriber has new voicemail messages waiting. Some units will also display the text "MESSAGE WAITING" (similar to ADSI
-compliant telephones). These units do not use visual FSK to activate their red LEDs, but instead, they briefly "pick-up" the line at certain intervals (normally, within two minutes of a new call) to check for a "stuttered" dial tone
. The presence of a stutter dial tone will activate a red LED; while absence will de-activate it.
s, the message-waiting indicator is sent via a Short Message Service
(SMS) message — the same system used for texting. (SMS was actually invented for utilitarian uses like this, not for user conversation.) It not only indicates that a message is waiting, but also how many unheard messages there are on the voicemail server
for that telephone number. In the event that a phone is deactivated, out of range, or otherwise removed from the network, there is often no way to clear this indicator until another message is recorded to the system, causing the MWI message to be sent again once the phone reconnects. The customer service
call center for the mobile network operator
may also be able to provide simple technical support
to reset this by resending the MWI message manually.
Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
, is a Telcordia Technologies
Telcordia Technologies
Telcordia Technologies, formerly Bell Communications Research, Inc. or Bellcore, is a telecommunications research and development company based in the United States created as part of the 1982 Modification of Final Judgment that broke up American Telephone & Telegraph...
(formerly Bellcore) term for an FSK
Frequency-shift keying
Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...
-based telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
calling feature that illuminates an LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
on select telephones to notify a telephone user of waiting voicemail
Voicemail
Voicemail 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 individuals, organizations, products and services, using an ordinary telephone...
messages on most North American public telephone networks and PBXs.
As described in Telcordia Generic Requirements document GR-283-CORE, a Message_Waiting_Indicator (MWI) is a mechanism that informs the subscriber about the status of recorded messages. The subscriber may subscribe to a notification feature that makes use of the status of this MWI.
Difference to audible message waiting indicators
This feature is also frequently called (and abbreviated) as visual message waiting indicator (VMWI). A VMWI, as defined in Telcordia GR-1401-CORE, is a stored program controlled switching (SPCS) system feature that activates and deactivates a visual indicator on customer-premises equipmentCustomer-premises equipment
Customer-premises equipment or customer-provided equipment is any terminal and associated equipment located at a subscriber's premises and connected with a carrier's telecommunication channel at the demarcation point...
(CPE) to notify the customer that new messages are waiting. VMWI differs from existing features that use other message indicators, such as audible stuttered dial tone
Dial tone
A dial tone is a telephony signal used to indicate that the telephone exchange is working, has recognized an off-hook, and is ready to accept a call. The tone stops when the first numeral is dialed...
, in that it activates a visual indicator on the CPE. The visual indicator may be as simple as lighting or flashing a light-emitting diode
Light-emitting diode
A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...
(LED), or as advanced as displaying a special message on a liquid-crystal display (LCD).
This technology was introduced in 1995, with the introduction of CLASS-based calling features and ADSI
Analog Display Services Interface
Analog Display Services Interface is a telephony technology that is currently used in POTS or computer-based PBX telephone service. It works in conjunction with a screen-based telephone or other compatible CPE to provide the user with softkey access to telephone company or internal PBX custom...
. It was at one time only compatible with ADSI
Analog Display Services Interface
Analog Display Services Interface is a telephony technology that is currently used in POTS or computer-based PBX telephone service. It works in conjunction with a screen-based telephone or other compatible CPE to provide the user with softkey access to telephone company or internal PBX custom...
-compliant telephones but is now compatible with any customer premises equipment (CPE
CPE
-Biochemistry:* Carboxypeptidase E* Clostridium perfringens enterotoxin* Cytopathic effect* Cytoplasmic polyadenylation element-Telecommunications:...
) that simply responds visually to visual FSK
Frequency-shift keying
Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK . BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the "1" is called...
.
Use of similar indicator on standalone Caller ID set-top boxes
This service is often erroneously associated with the abilities of most Caller IDCaller ID
Caller ID , also called calling line identification or calling number identification or Calling Line Identification Presentation , is a telephone service, available in analog and digital phone systems and most Voice over Internet Protocol applications, that transmits a caller's number to...
standalone set-top boxes. Caller ID boxes manufactured after 1998 feature an LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
that blinks green to notify that new calls have been recorded and red to indicate that a subscriber has new voicemail messages waiting. Some units will also display the text "MESSAGE WAITING" (similar to ADSI
Analog Display Services Interface
Analog Display Services Interface is a telephony technology that is currently used in POTS or computer-based PBX telephone service. It works in conjunction with a screen-based telephone or other compatible CPE to provide the user with softkey access to telephone company or internal PBX custom...
-compliant telephones). These units do not use visual FSK to activate their red LEDs, but instead, they briefly "pick-up" the line at certain intervals (normally, within two minutes of a new call) to check for a "stuttered" dial tone
Dial tone
A dial tone is a telephony signal used to indicate that the telephone exchange is working, has recognized an off-hook, and is ready to accept a call. The tone stops when the first numeral is dialed...
. The presence of a stutter dial tone will activate a red LED; while absence will de-activate it.
Mobile telephony
For mobile phoneMobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s, the message-waiting indicator is sent via a Short Message Service
Short message service
Short Message Service is a text messaging service component of phone, web, or mobile communication systems, using standardized communications protocols that allow the exchange of short text messages between fixed line or mobile phone devices...
(SMS) message — the same system used for texting. (SMS was actually invented for utilitarian uses like this, not for user conversation.) It not only indicates that a message is waiting, but also how many unheard messages there are on the voicemail server
Server (computing)
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...
for that telephone number. In the event that a phone is deactivated, out of range, or otherwise removed from the network, there is often no way to clear this indicator until another message is recorded to the system, causing the MWI message to be sent again once the phone reconnects. The customer service
Customer service
Customer service is the provision of service to customers before, during and after a purchase.According to Turban et al. , “Customer service is a series of activities designed to enhance the level of customer satisfaction – that is, the feeling that a product or service has met the customer...
call center for the mobile network operator
Mobile network operator
A mobile network operator , also known as mobile phone operator , carrier service provider , wireless service provider, wireless carrier, or cellular company, or mobile network carrier is a telephone company that provides services for mobile phone subscribers.One essential...
may also be able to provide simple technical support
Technical support
Technical support or tech support refers to a range of services by which enterprises provide assistance to users of technology products such as mobile phones, televisions, computers, software products or other electronic or mechanical goods...
to reset this by resending the MWI message manually.