Technical data

www.westermo.com Theoretical and general applications 89
Services on the GSM network
There are a number of services available via GSM such as:
… Telephony
… CSD (Circuit Switched Data, data transfer).
… SMS (Short Message Service).
… MMS (Multimedia Message Service).
… FAX.
… GPRS (General Packet Radio Service).
Telephony
The most common GSM service, which has contributed towards its global usage. The
algorithms to code and decode traffic have been under constant development, which
has resulted in the continuous minimization of the bandwidth for telephony while
maintaining the transmission quality.
Circuit Switched Data
The transfer of data, speeds from 2400 bit/s up to 14.4 kbit/s are possible. The table
opposite shows the available speeds and protocols.
Data communication can be set up for transparent or non transparent data transfer.
RLP (Radio Link Protocol) is used in non transparent transfer; this is an error correct-
ed GSM protocol. This protocol creates a more reliable transfer, but also generates
delays in the transfer. In order to use this function requires the support of both the
service and the connected devices.
Speed Protocol
2400 bit/s V.22 bis
4800 bit/s V.32
9600 bit/s V.32
14400 bit/s V.32 bis
2400 bit/s V.110
4800 bit/s V.110
9600 bit/s V.110
14400 bit/s V.110
B A C K