Year   Activity
Ericsson develops Mobitex in conjunction with the Swedish PTT Televerket as a portable alarm system for isolated workers
1986 The first public Mobitex network opens in Scandinavia
1989 Cantel opens the first North American Mobitex network in Canada
1990 RAM Mobile Data founded
1994 RAM Mobile Data claims more than 27,000 subscribers by the end of the year
2004 In October, Cingular Wireless spun off Cingular Interactive (which included the Mobitex network) to an affiliate of Cerberus Capital Management, which changed its name to Velocita Wireless.
2006 In February, Sprint/Nextel completes their acquisition of Velocita Wireless.

Base stations transmit between 935 and 940 MHz at up to 46 dBm and typically have between 1 and 4 channels.
Mobiles transmit between 896 and 901 MHz, up to 40 dBm (33 dBm for handhelds).

Time Division Multiple Access using modified slotted Aloha channel access.

Protected data rate is 4.6 kbps, with a maximum size of 512 bytes.

Frame starts with 56-bit header, bit and frame synchronization (16 bits each), base station and country identifier (12 + 4), CRC (8 bits).
Data blocks are 160 bits: 144 data bits and 16 bits of CRC. These 160 bits are coded with a shortened (12,8) Hammng code. Total block length is 240 bits.

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Last updated June 20, 2009