Các dịch vụ được cung cấp tại ± người dùng giao diện mạng (UNI) của GSM thường là màu sau khi dịch vụ được cung cấp bởi các dịch vụ kỹ thuật số tích hợp Network (ISDN) [7] cho ® xed thiết bị đầu cuối gắn với các dòng máy điện thoại. dịch vụ GSM do đó chia giống như dịch vụ ISDN thành ba loại: dịch vụ không ghi tên, teleservices, và các dịch vụ bổ sung. Một dịch vụ không ghi tên cung cấp các khả năng kỹ thuật cơ bản cho việc truyền tải dữ liệu nhị. | GSM Switching Services and Protocols . Second Edition. Jörg Eberspächer Hans-Jörg Vögel and Christian Bettstetter Copyright 2001 John Wiley Sons Ltd Print ISBN 0-471-49903-X Online ISBN 0-470-84174-5 4 Services The services offered at the User-Network Interface UNI of GSM are patterned after the services offered by the Integrated Services Digital Network ISDN 7 for fixed terminals tied to telephone lines. GSM services are therefore divided just like ISDN services into three categories bearer services teleservices and supplementary services. A bearer service offers the basic technical capability for the transmission of binary data . it offers the data transfer between end terminals at reference points R or S of the Reference Model Figures and . Such bearer services are made use of by the teleservices for the transfer of data with higher-level protocols. Figure Bearer and teleservices Notice that bearer and teleservices both require special measures not only at the air interface but also inside the PLMN which must offer a matching fixed-net infrastructure and special Interworking Functions IWFs . Especially at the level of bearer services the IWF must provide a mapping of GSM PLMN services within their respective service characteristics onto corresponding bearer services and characteristics of the other networks such as PSTN and ISDN. Teleservices are end-to-end services for which there is usually no translation in the IWF. But they do use bearer services which again need IWF functions. Bearer and teleservices are carried under the umbrella term telecommunication services. The simultaneous use of two telecommunication services is precluded except for the case of Short Message Services SMS which can at least be received during the use of another telecommunication service. Supplementary services are complementing the control and modification of extended services and are only usable in connection with a telecommunication service. 48 4 Services For .
