Integrated Digital Enhanced Network
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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 has been called the first mobile social network by 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).
The iDEN project originally began as MIRS (Motorola Integrated Radio System) in early 1991. The project was a software lab experiment focused on the utilization of discontiguous spectrum for GSM wireless. GSM systems typically require 24 contiguous voice channels, but the original MIRS software platform dynamically selected fragmented channels in the radio frequency (RF) spectrum in such a way that a GSM telecom switch could commence a phone call the same as it would in the contiguous channel scenario. The original MIRS System was renamed IDEN in 1994 by Roger Cameron Wood, a young engineering program manager leading the product development effort who also gave the handsets their distinctive industrial design, group software features, and "chirp" audio cue.
Operating frequencies 
iDEN is designed and licensed to operate on individual frequencies that may not be contiguous. iDEN operates on 25 kHz channels, but only occupies 20 kHz in order to provide interference protection via guard bands. By comparison, TDMA Cellular (Digital AMPS) is licensed in blocks of 30 kHz channels, but each emission occupies 40 kHz, and is capable of serving the same number of subscribers per channel as iDEN. iDEN uses frequency-division duplexing to transmit and receive signals separately, with transmit and receive bands separated by 39 MHz, 45 MHz, or 48 MHz depending on the frequency band being used.
iDEN supports either three or six interconnect users (phone users) per channel, and six dispatch users (push-to-talk users) per channel, using time division multiple access. The transmit and receive time slots assigned to each user are deliberately offset in time so that a single user never needs to transmit and receive at the same time. This eliminates the need for a duplexer at the mobile end, since time-division duplexing of RF section usage can be performed.
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The first commercial iDEN handset was Motorola's L3000, which was released in 1994. Most modern iDEN handsets use SIM cards, similar to, but incompatible with GSM handsets' SIM cards. Early iDEN models such as the i1000plus stored all subscriber information inside the handset itself, requiring the data to be downloaded and transferred should the subscriber want to switch handsets. Newer handsets using SIM technology make upgrading or changing handsets as easy as swapping the SIM card. Four different sized SIM cards exist, "Endeavor" SIMs are used only with the i2000 without data, "Condor" SIMs are used with the two-digit models (i95cl, for example) using a SIM with less memory than the three-digit models (i730, i860), "Falcon" SIMs are used in the three-digit phones, (i530, i710) and will read the smaller SIM for backward compatibility, but some advanced features such as extra contact information is not supported by the older SIM cards. There is also the "Falcon 128" SIM, which is the same as the original "Falcon", but doubled in memory size, which is used on new 3 digit phones (i560, i930).
The interconnect-side of the iDEN network uses GSM signalling for call set-up and mobility management, with the Abis protocol stack modified to support iDEN's additional features. Motorola has named this modified stack 'Mobis'.
Each base site requires precise timing and location information to synchronize data across the network. To obtain and maintain this information each base site uses global positioning system satellites to receive a precise timing reference.
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In the United States of America there are two large public iDEN service providers: Sprint Nextel and SouthernLINC Wireless, and several small public and private iDEN service providers. Numerous private systems exist, including one run by ARINC, covering all major airports. Countries which have operating iDEN networks include Canada, Argentina, Peru, Mexico, Brazil, Jordan, Chile, Israel, Philippines, Singapore, Saudi Arabia, Japan, El Salvador, China and most recently India and Guatemala. Full Roaming is available between Sprint/Nextel in the US, Telus (Canada), and NII (Mexico and South American markets) Data/Voice/Radio. For markets not controlled by NII Holdings, Inc., the roaming is for voice telephony only.
Motorola is committed to support of iDEN technology despite the Sprint buyout of Nextel and Sprint/Nextel's supposed eventual conversion to Sprint's CDMA system. Sprint/Nextel has stated they will support iDEN until June 2013 and Sprint has maintained their iDEN holdings with the purchase of the Sprint CDMA affiliate network, iPCS, for $426 million, which Sprint was repeatedly engaged in lawsuits over non-compete agreement violations stemming from the 2005 purchase of Nextel and the later purchase of Nextel Partners. Other iDEN carriers have no foreseeable expiration date for their services. The speed of iDEN's push-to-talk (a.k.a. dispatch) feature remains the fastest in the industry as compared to Sprint Qchat [Qualcomm PTT over EVDO Rev. A] and Verizon PTT [requiring at least 1XRTT data] in the US.
In November, 2012, Sprint announced a $10 monthly surcharge for iDEN users. Reports speculate that this surcharge is meant to encourage faster migration to CDMA push-to-talk.
There is a smaller subset of the iDEN network called "Harmony Wireless Communications System". With Small System Release 7.0, it supports a maximum site count of 160 or 576 individual cells. Harmony has the ability to interface with a full iDEN system, and has the ability to support interconnect, dispatch, and packet data. SSR7.1 is the latest Harmony release[original research?].
iDEN network operators 
|Network operator||Country||Push-to-Talk product name|
|Airpeak||United States||Talk Direct|
|Airtel Wireless Ltd.||Canada||Churp|
|Bravo Telecom||Saudi Arabia||Push To Talk|
|China Satcom Guomai Comm Co. Ltd||China|
|Connect Net||United States|
|GRID Communications||Singapore||Push To Talk|
|Iconnect||China Hong Kong (SAR)|
|KT Powertel||South Korea|
|Nextel Argentina||Argentina||Direct Connect|
|Nextel Brazil||Brazil||Direct Connect|
|Nextel Chile||Chile||Direct Connect|
|Nextel Mexico||Mexico||Conexión Directa|
|Nextel Peru||Peru||Conexión Directa|
|Procall Pvt. Ltd.||India||Digital Push To Talk|
|Proxtel Wireless||Puerto Rico||Direct Connect|
|Shenzhen Yunliantong Comm Service||China|
|SouthernLINC Wireless||United States||InstantLINC|
|Sprint Nextel (Boost Mobile)||United States||Direct Connect|
|XPress||Jordan||XPress Direct Connect|
See also 
- Lawson, Stephen (December 7, 2010). "Sprint's iDEN finally headed for sign-off". Computerworld.com. Retrieved 5 September 2012.
- Motorola iDEN Technical Overview
- "Sprint tacks $10 charge on to iDEN subscribers not on CDMA". Retrieved 30 November 2012.