Multi-frequency signaling

In telephony, multi-frequency signaling (MF) is an outdated, in-band signaling technique. Numbers were represented in a two-out-of-five code for transmission from a multi-frequency sender, to be received by a multi-frequency receiver in a distant telephone exchange. MF was used for signaling in trunking applications, and is a precursor of modern DTMF signaling (TouchTone) now used for subscriber signaling.

Using MF signaling, the originating telephone switching office sends a starting signal such as a seizure (off-hook) by toggling the AB bits. After the initial seizure, the terminating office acknowledges a ready state by responding with a wink (short duration seizure) and then goes back on-hook (wink start). The originating office sends the destination digits to the terminating switch.

MF and other in-band signaling systems differ from Signaling System 7 (SS7) in that the routing digits are out-pulsed in MF format in the same voiceband channel used for voice. The user dialing cannot detect these digits being out-pulsed because the audio connection is not established all the way to the user’s handset or device until after the connection is established with the terminating switch. Following a full connection, the same audio channel is connected to the user in order to communicate the voice, modem or fax data across that same 64-kbit channel previously used for the in-band MF signaling.

Out-of-band Common Channel Signaling is nearly universal today in the United States. Benefits include higher connection establishment rate, more fraud security (antiphreaking measures), and features such as Caller ID; however, some 911 Public Safety Answering Points (PSAPs) still use the MF format to process calls from Mobile Telephone Switching Offices (MTSOs) and land telephone offices. Other countries may still use a version of in-band signaling.

MF signaling includes R2 signaling, R1^[1] (in North America), and Signaling System No. 5.

See also

• blue box

References

1. ^ ITU-T Recommendation Q.310-Q.332 - Specification of Signalling System R1

This article related to telecommunications is a stub. You can help Wikipedia by expanding it.v · Categories: Telephony signals Telecommunications stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем написать реферат The Society for the Study of the Multi-Ethnic Literature of the United States Multiclass classification Look at other dictionaries: Dual-tone multi-frequency signaling — One of the few production telephone DTMF keypads with all 16 keys, from an Autovon Telephone. The column of red keys produces the A, B, C, and D DTMF events. Dual tone multi frequency signaling (DTMF) is used for telecommunication signaling over… …   Wikipedia Multi-frequency receiver — Multi Frequency signalling, (MF), is similar to the European version, CCITT Signaling System 5, (SS5). The original format was five tones used in pairs. This later evolved to six tones. Because its six tones are used only in pairs, this signaling …   Wikipedia Multi-frequency — In telephony Multi Frequency (MF) is an outdated, in band signaling technique. Numbers were represented in a two out of five code for transmission from a Multi Frequency Sender, to be received by a Multi frequency receiver in a distant telephone… …   Wikipedia Dual-tone multi-frequency — (DTMF) signaling is used for telephone signaling over the line in the voice frequency band to the call switching center. The version of DTMF used for telephone tone dialing is known by the trademarked term Touch Tone (canceled March 13, 1984),… …   Wikipedia Signaling (telecommunications) — In telecommunication, signaling (signalling in British spelling) has the following meanings: the use of signals for controlling communications the information exchange concerning the establishment and control of a telecommunication circuit and… …   Wikipedia Signaling System 7 — Signaling System #7 (SS7) is a set of telephony signaling protocols which are used to set up most of the world s public switched telephone network telephone calls. The main purpose is to set up and tear down telephone calls. Other uses include… …   Wikipedia Multi-Use Radio Service — In the United States, the Multi Use Radio Service (MURS) is an unlicensed two way radio service similar to Citizens Band (CB). Established by the U.S. Federal Communications Commission in the fall of 2000, MURS created a radio service allowing… …   Wikipedia Signaling System No. 5 — CCITT5 [http://www.itu.int/rec/T REC Q.140 Q.180/en ITU T Recommendation Q.140 Q.180] Specifications of Signalling System No. 5] was a multi frequency (MF) telephone signalling system in use from the 1970s for International Direct Distance… …   Wikipedia Frequency-shift keying — Passband modulation v · d · e Analog modulation AM · …   Wikipedia Multi-gigabit transceiver — A Multi Gigabit Transceiver (MGT) is a SerDes capable of operating at serial bit rates above 1 Gigabit/second. MGTs are used increasingly for data communications because they can run over longer distances, use fewer wires, and thus have lower… …   Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”