 | This article provides insufficient context for those unfamiliar with the subject.(October 2009) |
A system identification number (SID) is broadcast by one or more base stations to identify a cellular network in a certain area (usually contiguous). It is globally unique within AMPS, TDMA or CDMA networks (the first two systems are essentially obsolete). This number sometimes has conflicts (see IFAST).
These codes are broadcast as 15 bit values but transmitted as 16 bits by core network protocols. They can be listed within a wireless device to show preference for one network over another. The additional bit in core network protocols allows the range of codes above 32,767 to be used for internal purposes, such as segregating billing records within a large area identified by a single broadcast SID.
Telecommunications Industry Association committee TR-45.2 assigned ranges to every country extant in the 1980s and national regulators assigned individual numbers. IFAST took over in 1997. This number space is 90% utilized for country ranges. Many countries do not use all of their allocated codes, hence the majority of codes are unused.
SIDs are assigned to every carrier (e.g., Verizon, Sprint, Alltel) by national regulators or IFAST. SIDs are programmed into the phone when purchased. A phone will maintain a list of "preferred" systems identified by their SID code. The SID may also modify some signaling messages that are transmitted by mobiles (e.g. reducing the amount of information transmitted by "home" mobiles).
When the phone is turned on, it listens for a signal. If it receives a signal, it looks at the SID carried by the signal, and compares it with the one that is stored in the phone. Originally, in analog systems, the mobile would turn on the roaming indicator if the SID was not the single value stored in the phone.
With CDMA systems the Preferred Roaming List (PRL) is responsible for determining which areas a mobile can roam into. Base stations may also broadcast an MCC and MNC which can also be used by the PRL.
www.nqr.gov.in
Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. This allows several users to share a band of frequencies. To permit this without undue interference between the users, CDMA employs spread spectrum technology and a special coding scheme.
General Packet Radio Service (GPRS), also called 2.5G, is a packet orientated mobile data standard on the 2G cellular communication network's global system for mobile communications (GSM). GPRS was established by European Telecommunications Standards Institute (ETSI) in response to the earlier CDPD and i-mode packet-switched cellular technologies. It is now maintained by the 3rd Generation Partnership Project (3GPP).
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.
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, UMTS is a component of the International Telecommunication Union IMT-2000 standard set and compares with the CDMA2000 standard set for networks based on the competing cdmaOne technology. UMTS uses wideband code-division multiple access (W-CDMA) radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators.
In telecommunications and computer networks, a channel access method or multiple access method allows more than two terminals connected to the same transmission medium to transmit over it and to share its capacity. Examples of shared physical media are wireless networks, bus networks, ring networks and point-to-point links operating in half-duplex mode.
Interim Standard 95 (IS-95) was the first digital cellular technology that used code-division multiple access (CDMA). It was developed by Qualcomm and later adopted as a standard by the Telecommunications Industry Association in TIA/EIA/IS-95 release published in 1995. The proprietary name for IS-95 is cdmaOne.
Frequency-division multiple access (FDMA) is a channel access method used in some multiple-access protocols. FDMA allows multiple users to send data through a single communication channel, such as a coaxial cable or microwave beam, by dividing the bandwidth of the channel into separate non-overlapping frequency sub-channels and allocating each sub-channel to a separate user. Users can send data through a subchannel by modulating it on a carrier wave at the subchannel's frequency. It is used in satellite communication systems and telephone trunklines.
Roaming is a wireless telecommunication term typically used with mobile devices, such as mobile phones. It refers to a mobile phone being used outside the range of its native network and connecting to another available cell network.
IS-54 and IS-136 are second-generation (2G) mobile phone systems, known as Digital AMPS (D-AMPS), and most often referred to as TDMA, are a further development of the North American 1G mobile system Advanced Mobile Phone System (AMPS). It was once prevalent throughout the Americas, particularly in the United States and Canada since the first commercial network was deployed in 1993. D-AMPS is considered end-of-life, and existing networks have mostly been replaced by GSM/GPRS or CDMA2000 technologies.
Network switching subsystem (NSS) is the component of a GSM system that carries out call out and mobility management functions for mobile phones roaming on the network of base stations. It is owned and deployed by mobile phone operators and allows mobile devices to communicate with each other and telephones in the wider public switched telephone network (PSTN). The architecture contains specific features and functions which are needed because the phones are not fixed in one location.
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.
The Preferred Roaming List (PRL) is a database residing in a wireless device, such as a cellphone, that contains information used during the system selection and acquisition process. In the case of R-UIM-based CDMA devices, the PRL resides on the R-UIM. The PRL indicates which bands, sub bands, and service provider identifiers will be scanned and in what priority order. Without a PRL, the device may not be able to roam, i.e. obtain service outside of the home area. There may be cases where missing or corrupt PRLs can lead to a customer not having service at all.
A mobile phone feature is a capability, service, or application that a mobile phone offers to its users. Mobile phones are often referred to as feature phones, and offer basic telephony. Handsets with more advanced computing ability through the use of native code try to differentiate their own products by implementing additional functions to make them more attractive to consumers. This has led to great innovation in mobile phone development over the past 20 years.
International Forum on ANSI-41 Standards Technology (IFAST) is the coordinator for the allocation of System Identification Numbers (SID) for wireless communication outside Canada, the United States and territories, and on the assignment of International Roaming mobile identification numbers (MINs), or IRM, for use in cellular mobile devices.
This is a comparison of standards of wireless networking technologies for devices such as mobile phones. A new generation of cellular standards has appeared approximately every tenth year since 1G systems were introduced in 1979 and the early to mid-1980s.
A mobile equipment identifier (MEID) is a globally unique number identifying a physical piece of CDMA2000 mobile station equipment. The number format is defined by the 3GPP2 report S.R0048 but in practical terms, it can be seen as an IMEI but with hexadecimal digits.
Phone cloning is the copying of identity from one cellular device to another.
A mobile phone signal is the signal strength received by a mobile phone from a cellular network. Depending on various factors, such as proximity to a tower, any obstructions such as buildings or trees, etc. this signal strength will vary. Most mobile devices use a set of bars of increasing height to display the approximate strength of this received signal to the mobile phone user. Traditionally five bars are used.
Cellular frequencies are the sets of frequency ranges within the ultra high frequency band that have been assigned for cellular-compatible mobile devices, such as mobile phones, to connect to cellular networks. Most mobile networks worldwide use portions of the radio frequency spectrum, allocated to the mobile service, for the transmission and reception of their signals. The particular bands may also be shared with other radiocommunication services, e.g. broadcasting service, and fixed service operation.