advanced speech call item (GSM, BOS) (ASCI)

Advanced Speech Call Items (ASCI) are GSM services specially designed for public authorities, the railroads and various organizations. They are services that are necessary for specific areas of operation and are supported by GSM.

ASCI services used in GSM- BOS and GSM-R include Location Dependent Addressing(LDA), Functional Addressing ( FA), Voice CommunicationGroup Calling(VGCS), and Group Calling Service ( VBS).

Location dependent addressing is necessary to enable the control center to contact subscribers regardless of their location. For this purpose, the functional identification number, with which the network is able to contact the subscriber on the basis of the function performed, is an essential prerequisite. This identification number is known as the Mobile Subscriber ISDN Number( MSISDN).