Editing Frequency-shift keying (section)

==Caller ID and remote metering standards==
Frequency-shift keying (FSK) is commonly used over telephone lines for [[caller ID]] (displaying callers' numbers) and [[remote metering]] applications. There are several variations of this technology.

===European Telecommunications Standards Institute===
In some countries of [[Europe]], the [[European Telecommunications Standards Institute]] (ETSI) standards 200 778-1 and -2 &ndash; replacing 300 778-1 & -2 &ndash; allow 3 physical transport layers ([[Telcordia Technologies]] (formerly Bellcore), [[British Telecom]] (BT) and [[Cable Communications Association]] (CCA)), combined with 2 data formats [[Caller ID|Multiple Data Message Format]] (MDMF) & [[Caller ID|Single Data Message Format]] (SDMF), plus the [[Dual-tone multi-frequency]] (DTMF) system and a no-ring mode for meter-reading and the like. It's more of a recognition that the different types exist than an attempt to define a single "standard".

===Telcordia Technologies===
The [[Telcordia Technologies]] (formerly Bellcore) standard is used in the [[United States]], Canada (but see below), [[Australia]], [[China]], [[Hong Kong]] and [[Singapore]]. It sends the data after the first ring tone and uses the 1200 [[Bit rate|bits per second]] [[Bell 202]] tone modulation. The data may be sent in SDMF &ndash; which includes the date, time and number &ndash; or in MDMF, which adds a NAME field.

===British Telecom===
[[British Telecom]] (BT) in the [[United Kingdom]] developed their own standard, which wakes up the display with a line reversal, then sends the data as [[ITU-T|CCITT]] v.23 modem tones in a format similar to MDMF. It is used by BT, wireless networks like the late [[Ionica (company)|Ionica]], and some cable companies. Details are to be found in BT [[Supplier Information Note]]s (SINs) [http://www.sinet.bt.com/sinet/SINs/pdf/227v3p6.pdf 227] {{Webarchive|url=https://web.archive.org/web/20140726125549/http://www.sinet.bt.com/sinet/SINs/pdf/227v3p6.pdf |date=2014-07-26 }}(link broken 28/7/21) and [http://www.sinet.bt.com/sinet/SINs/pdf/242v2p4.pdf 242] {{Webarchive|url=https://web.archive.org/web/20140726130003/http://www.sinet.bt.com/sinet/SINs/pdf/242v2p4.pdf |date=2014-07-26 }}(link broken 28/7/21); another useful document is [http://www.exar.com/common/content/document.ashx?id=248 Designing Caller Identification Delivery Using XR-2211 for BT] {{Webarchive|url=https://web.archive.org/web/20160306003503/http://www.exar.com/common/content/document.ashx?id=248 |date=2016-03-06 }} from the [[EXAR]] website.

===Cable Communications Association===
The [[Cable Communications Association]] (CCA) of the United Kingdom developed their own standard which sends the information after a short first ring, as either [[Bell 202 modem|Bell 202]] or [[ITU V.23|V.23]] tones. They developed a new standard rather than change some "street boxes" (multiplexors) which couldn't cope with the BT standard. The UK cable industry use a variety of switches: most are [[Nortel]] DMS-100; some are [[System X (telephony)|System X]]; [[System Y]]; and [[Nokia]] DX220. Note that some of these use the BT standard instead of the CCA one. The data format is similar to the BT one, but the transport layer is more like Telcordia Technologies, so [[North America]]n or European equipment is more likely to detect it.