★ The services offered by GSM are ISDN compatible

★ GSM allows synchronous data and asynchronous data to be transported as bearer service, one of the telecommunication services offered by GSM, and forms ISDN terminal

★ The data could be either transparent service or nontransparent service

★ Telephony is one of the services offered by GSM, which an emergency and the service provider is notified by dialing 3 digits

★ By using appropriate fax adapter, G3 fax service is supported

★ One of the features of GSM is Short Messaging Service

★ Certain services, namely supplementary services are provided on top of teleservices or bearer services by GSM, such as, caller identification, call forwarding, multiparty conversations, barring outgoing calls and call waiting.