Mobitex 8000 is a multiple access packet radio system for wireless communications developed from the older Mobitex 1200 bps system. Mobitex 8000 operates in the UHF bands and is found around 420 and 900 MHz in a number of countries using direct 8 kbps GMSK modulation.

The Mobitex 8000 frames consist of a frame header with a unique synchronization word, base station identification, traffic area identification and control flags followed by zero or more blocks of data, max 32 blocks. Each block consists of 18 bytes followed by two CRC bytes.

The data block bytes are protected by a 4-bit (12, 8) Hamming code so each data word is 12 bits long. For further protection the data bits are interleaved. However, the frame header is not interleaved and does not have a CRC sum appended.

Each system is identified by the unique 4 hexadecimal digit sync word. The sync word is inverted for mobile-base communication.

The first data block contains addressing information, frame type id, number of blocks and other control information. Frames can either be data link frames used for the management of traffic or payload data frames called MRM frames. The payload frames contain so called MPAKs, i.e., Mobitex Packets which can have a total length of 512 bits. If the message is longer it is split into a number of sequences.

The first payload data block contains MPAK header information: source and destination addresses, subscription flags, packet class and packet type information and a timestamp if they are transmitted in the base-to-mobile direction. The remote terminals do not insert a time stamp, this is done by the network.

The system has two payload packet classes, PSUBCOM for subscriber packet switched communication and DTESERV for service messages.

PSUBCOM will accommodate text (7-bit ASCII text), data (transparent data), status messages (transparent data) and higher protocol data identified by a protocol identification byte after the time stamp.