GSM was conceived in accordance with the guidelines of ISDN. Therefore, a reference con®guration is also de®ned for GSM systems, similar to the one used in ISDN systems. Using the reference con®guration, one gets an impression of the range of services and the kinds of interfaces to be provided by mobile stations. Furthermore, the reference con®guration indicates at which interface which protocols or functions terminate and where adaptation functions may have to be provided. The GSM reference con®guration comprises the functional blocks of a mobile station (Figure ) at the user±network interface Um. . | 9 GSM Switching Services and Protocols . Second Edition. Jôrg Eberspâcher Hans-Jorg Vogel and Christian Bettstetter Copyright 2001 John Wiley Sons Ltd Print ISBN 0-471-49903-X Online ISBN 0-470-84174-5 Data Communication and Networking Reference Configuration GSM was conceived in accordance with the guidelines of ISDN. Therefore a reference configuration is also defined for GSM systems similar to the one used in ISDN systems. Using the reference configuration one gets an impression of the range of services and the kinds of interfaces to be provided by mobile stations. Furthermore the reference configuration indicates at which interface which protocols or functions terminate and where adaptation functions may have to be provided. The GSM reference configuration comprises the functional blocks of a mobile station Figure at the user-network interface Um. The mobile equipment is subdivided into a Mobile Termination MT and various combinations of Terminal Adapter TA and Terminal Equipment TE depending on the kind of service access and interfaces offered to the subscriber. At the interface to the mobile network the air interface Um MT units are defined. An integrated mobile speech or data terminal is represented only by an MTO. The MT1 unit goes one step further and offers an interface for standard-conforming equipment at the ISDN S reference point which can be connected directly as end equipment. Likewise normal data terminal equipment with a standard interface . can be connected via a TA and this way use the mobile transmission services. Finally the TA functionality has been integrated into units of type MT2. At the S or R reference point the GSM bearer or data services are available access points 1 and 2 in Figure whereas the teleservices are offered at the user interfaces of the TE access point 3 Figure . Among the bearer services besides the transmission of digitized speech there are circuit-switched and packet-switched data transmission. .
