03.603GPPGeneral Packet Radio Service (GPRS)Release 1998Service descriptionStage 2TS
The Packet Terminal Adaptation function adapts packets received from and transmitted to the Terminal Equipment to a form suitable for transmission within GSM.
A range of MT versions providing different standard interfaces towards the TE can be used, e.g.:
– MT with asynchronous serial interface and PAD (Packet Assembly / Disassembly) support (e.g., AT command set PAD, X.28  / X.29  / X.3  PAD). In the case when the PAD function does not exist in the MT, it exists in the TE;
– "Embedded MT" integrated with the TE, possibly via an industry-standard application program interface;
– MT with synchronous serial interface.