This European Telecommunication Standard (ETS) specifies the stage one description of the Voice Group Call Service (VGCS) which allows speec h conversation of a predefined group of service subscribers in half du plex mode on the radio link taking into account multiple mobile servic e subscribers involved in the VGCS call per cell. The VGCS is applicable to all mobile stations in a certain network and area which have the technical capability and the corresponding subscr iption, respectively, to participate in a VGCS call. NOTE: It is not considered as requirement that normal GSM phase 2 mobi le stations will be able to be used for this service. The service is described from the service subscriber s and user s poin t of view; in particular: - the procedure for normal operation with successful outcome; - the action to be taken in exceptional circumstances; - the interaction with other GSM services and features. This ETS does not deal with the Man-Machine Interface (MMI) requiremen ts, but makes reference to the appropriate Global System for Mobile Co mmunications (GSM) specifications. This ETS defines a teleservice of the digital cellular telecommunicati ons system GSM. Any interaction with other services and/or networks no t dealt with in clauses 8 or 9 are outside the scope of this ETS.