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CT2 is a cordless telephony standard that was used in the early 1990s to provide short-range proto-mobile phone service in some countries in Europe and in Hong Kong. It is considered the precursor to the more successful DECT system. CT2 was also referred to by its marketing name, Telepoint.
CT2 is a digital FDMA system that uses time-division duplexing technology to share carrier frequencies between handsets and base stations. Features [1] [2] [3] of the system are:
Unlike DECT, CT2 was a voice-only system, though like any minimally-compressed voice system, users could deploy analog modems to transfer data; in the early 1990s, Apple Computer sold a CT2 modem called the PowerBop to make use of France's Bi-Bop CT2 network. Although CT2 is a microcellular system, fully capable of supporting handoff, unlike DECT it does not support "forward handoff", meaning that it has to drop its former radio link before establishing the subsequent one, leading to a sub-second dropout in the call during the handover.
CT2 was deployed in a number of countries, including Britain and France. In Britain, the Ferranti Zonephone system was the first public network to go live in 1989, and the much larger Rabbit network – backed by Hong Kong's Hutchison Telecommunications – operated from 1992 to 1993. [4] In France, the Bi-Bop network ran from 1991 to 1997. In the Netherlands, Dutch incumbent PTT deployed a CT2-based network called Greenpoint from 1992 to 1999; in the first year it used the name and mascot Kermit but royalties proved prohibitively large and the mascot was dropped. [5] The service continued under the brand name Greenhopper, with at one time over 60,000 subscribers. In Finland, the Pointer service was available for a short time in the 1980s before being superseded by Nordic Mobile Telephone (NMT). Since 31 December 2008, CTA1 and CTA2 based phones are forbidden in Germany.
Outside Europe, the system achieved a certain amount of popularity in Hong Kong with three operators offering service from 1991, until licenses were terminated in 1996. [6] A CT2 service was offered in Singapore from 1993 to 1998 by Telecommunications Equipment under the brand name Callzone, [7] [8] using Motorola's Silverlink 2000 Birdie handset.
Typical CT2 users were sold a handset and base station which they could connect to their own home telephone wiring. Calls via the home base station would be routed via the home telephone line and in this configuration the system was identical to a standard cordless phone, for both incoming and outgoing calls.
Once out of range of the home, the CT2 user could find signs indicating a network base station in the area, and make outgoing calls (but not receive calls) using the network base station. Base stations were in a variety of places, including high-streets and other shopping areas, gas stations, and transport hubs such as rail stations. In this configuration, callers would be charged a per-minute rate which was higher than if they made calls from home, but not as high as conventional cellular charges.
The advantages to the user were that the rates were generally lower than cellular, and that the same handset could be used at home and away from home. The disadvantages, compared to cellular, were that many networks did not deliver incoming calls to the phones (Bi-Bop was an exception), and that their areas of use were more limited.
There are no known open CT2 networks still running.
Japan's Personal Handyphone System, another system based upon microcells, is a direct analog of CT2 and has achieved a much greater level of success. PHS is a full microcellular system with hand-off, better range, and more features.
The DECT system is CT2's successor, and also supports full microcellular service and data. However, to date DECT has been used to provide commercial mobile-phone like service only in Italy in 1997-8 (the FIDO network).
Canada adopted an enhanced version of CT2, known as CT2Plus, in 1993, operating in the 944–948.5 MHz band. CT2Plus class 2 systems benefited from the use of common signalling channels and offered multi-cell hand-off as well as tracking of devices. Incoming calls could be received anywhere within a multi-cell system. Nortel Networks offered a private branch exchange system based on the standard which was specified in Department of Communication document RSS-130 Annex 1.
In the United States, a system similar to DECT and PHS called PACS was developed but never deployed commercially.
CT2, as used in Europe and Hong Kong, required adherence to the MPT 1322 and MPT 1334 technical standards. Most striking was the use of TDD (time-division duplex) channels where one radio channel carried both sides of a duplex telephone conversation. This solved the problem of different propagation paths between two widely separated channels (up to 45 MHz in some cellular systems), but also placed an upper limit on the range of CT-2 signaling, since the speed of light (and radio signals) prevented long transmission paths. However, the use of TDD made available many frequency bands for CT-2 use, since a "paired" return path was not needed.
An American company, Cellular 21, Inc. (later to become Advanced Cordless Technologies, Inc.) headed by broadcaster Matt Edwards, petitioned the FCC to permit the use of CT2 technology in the US. ACT built two active test systems which were located in Monticello, New York (outdoor), and outside and inside the South Street Seaport complex in lower Manhattan. The Monticello public field trials used Timex technology which was incompatible with the trans-European standard, while the South Street Seaport indoor test used equipment from Ferranti, GPT, and Motorola, which at the time manufactured CT2 equipment for the Singapore and Hong Kong markets. GPT and Motorola both provided CT2 equipment for the Rabbit system rollout (GPT handset and charger shown above). All the testing was under an FCC Experimental license. The ACT/Cellular 21 "Petition for Rulemaking" (RM-7152), along with a later petition by Millicom, became the basis of the FCC's PCS initiative (FCC GEN Docket 90-314) which resulted in the allocation of frequencies in the 1.7 to 2.1 GHz band as spectrum expansion for the crowded 800 MHz cellular band. The FCC used the acronym PCS to designate Personal Communications Services, separate and distinct from cellular service which was 800 MHz analog at the time. PCS was to be digital-only, and has progressed through several "generations" (mostly marketing designations) such as G3 and G4.
Advanced Mobile Phone System (AMPS) was an analog mobile phone system standard originally developed by Bell Labs and later modified in a cooperative effort between Bell Labs and Motorola. It was officially introduced in the Americas on October 13, 1983, and was deployed in many other countries too, including Israel in 1986, Australia in 1987, Singapore in 1988, and Pakistan in 1990. It was the primary analog mobile phone system in North America through the 1980s and into the 2000s. As of February 18, 2008, carriers in the United States were no longer required to support AMPS and companies such as AT&T and Verizon Communications have discontinued this service permanently. AMPS was discontinued in Australia in September 2000, in India by October 2004, in Israel by January 2010, and Brazil by 2010.
Digital Enhanced Cordless Telecommunications, usually known by the acronym DECT, is a standard used for creating cordless telephone systems and for IoT systems. It originated in Europe, where it is the common standard, replacing earlier cordless phone standards, such as 900 MHz CT1 and CT2. The IoT usage relies on the new DECT-2020 standard.
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 electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. The term is derived from Greek: τῆλε and φωνή, together meaning distant voice. A common short form of the term is phone, which came into use early in the telephone's history. Nowadays, phones are almost always in the form of smartphones or mobile phones, due to technological convergence.
Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same transmission medium while using only a part of its channel capacity. Dynamic TDMA is a TDMA variant that dynamically reserves a variable number of time slots in each frame to variable bit-rate data streams, based on the traffic demand of each data stream.
In radio communication, a transceiver is an electronic device which is a combination of a radio transmitter and a receiver, hence the name. It can both transmit and receive radio waves using an antenna, for communication purposes. These two related functions are often combined in a single device to reduce manufacturing costs. The term is also used for other devices which can both transmit and receive through a communications channel, such as optical transceivers which transmit and receive light in optical fiber systems, and bus transceivers which transmit and receive digital data in computer data buses.
Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter. Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, satellite phones, and numerous other applications.
Integrated Digital Enhanced Network (iDEN) is a mobile telecommunications technology, developed by Motorola, which provides its users the benefits of a trunked radio and a cellular telephone. It was called the first mobile social network by many technology industry analysts. iDEN places more users in a given spectral space, compared to analog cellular and two-way radio systems, by using speech compression and time-division multiple access (TDMA).
A cellular network or mobile network is a telecommunications network where the link to and from end nodes is wireless and the network is distributed over land areas called cells, each served by at least one fixed-location transceiver. These base stations provide the cell with the network coverage which can be used for transmission of voice, data, and other types of content. A cell typically uses a different set of frequencies from neighboring cells, to avoid interference and provide guaranteed service quality within each cell.
A cordless telephone or portable telephone has a portable telephone handset that connects by radio to a base station connected to the public telephone network. The operational range is limited, usually to the same building or within some short distance from the base station.
A microcell is a cell in a mobile phone network served by a low power cellular base station (tower), covering a limited area such as a mall, a hotel, or a transportation hub. A microcell is usually larger than a picocell, though the distinction is not always clear. A microcell uses power control to limit the radius of its coverage area.
The Improved Mobile Telephone Service (IMTS) was a pre-cellular VHF/UHF radio system which linked to the public telephone network. IMTS was the radiotelephone equivalent of land dial phone service. Introduced in 1964, it replaced Mobile Telephone Service (MTS) and improved on most MTS systems by offering direct-dial rather than connections through a live operator, and full-duplex operation so both parties could talk at the same time.
The Generic Access Profile (GAP) describes a set of mandatory requirements to allow any conforming DECT Fixed Part (base) to interoperate with any conforming DECT Portable Part (handset) to provide basic telephony services when attached to a 3.1 kHz telephone network.
Mobile radio telephone systems were mobile telephony systems that preceded modern cellular network technology. Since they were the predecessors of the first generation of cellular telephones, these systems are sometimes retroactively referred to as pre-cellular systems. Technologies used in pre-cellular systems included the Push to Talk, Mobile Telephone Service (MTS), Improved Mobile Telephone Service (IMTS), and Advanced Mobile Telephone System (AMTS) systems. These early mobile telephone systems can be distinguished from earlier closed radiotelephone systems in that they were available as a commercial service that was part of the public switched telephone network, with their own telephone numbers, rather than part of a closed network such as a police radio or taxi dispatching system.
The history of mobile phones covers mobile communication devices that connect wirelessly to the public switched telephone network.
The Personal Handy-phone System (PHS), also marketed as the Personal Communication Telephone (PCT) in Thailand, and the Personal Access System (PAS) and commercially branded as Xiaolingtong in Mainland China, was a mobile network system operating in the 1880–1930 MHz frequency band, used mainly in Japan, China, Taiwan, and some other Asian countries and regions.
Wi-Fi calling refers to mobile phone voice calls and data that are made over IP networks using Wi-Fi, instead of the cell towers provided by cellular networks. Using this feature, compatible handsets are able to route regular cellular calls through a wireless LAN (Wi-Fi) network with broadband Internet, while seamlessly change connections between the two where necessary. This feature makes use of the Generic Access Network (GAN) protocol, also known as Unlicensed Mobile Access (UMA).
Mobile VoIP or simply mVoIP is an extension of mobility to a voice over IP network. Two types of communication are generally supported: cordless telephones using DECT or PCS protocols for short range or campus communications where all base stations are linked into the same LAN, and wider area communications using 3G or 4G protocols.
CT1 stands for Cordless telephone generation 1 and is an analog cordless telephone standard that was standardized by the European Conference of Postal and Telecommunications Administrations (CEPT) in 1984 and deployed in eleven European countries. The initial set of frequencies provided for a set 40 duplex channels using 25 kHz separation, with the phones transmitting in the 914-915 MHz band and the base stations in the 959-960 MHz band. These frequencies overlap with those used by channels 120-124 on GSM cellular phones and thus these original frequencies have been withdrawn from use for cordless phones in the countries that originally authorized them.
Dual-mode mobiles refer to mobile phones that are compatible with more than one form of data transmission or network.
Gigaset AG, formerly known as Siemens Home and Office Communication Devices, is a German multinational corporation based in Bocholt, Germany. More active in the area of communications technology, it manufactures DECT telephones.
