Advanced Speech Call Items (ASCI) are a special set of speech call services designed on top of GSM standard to fulfill the requirements of International Union of Railways (in French Union Internationale des Chemins de fer - UIC). In collaboration with ETSI, railways' working-group EIRENE formed a set of functional and system requirement specifications for mobile networks which would fulfill the needs of railways and insure interoperability across the borders. With new signaling and voice functionalities implemented, EIRENE-compliant network can be referred to as a GSM-Railway (GSM-R) network. In terms of voice communication, GSM-R system makes use of standard 2G mobile networks' speech services, as well as newly-defined ASCI services. Basic purpose of ASCI services for railways is to provide the distribution of speech into a predefined geographical area, towards all or towards only a group of service subscribers located in that area. Therefore, Voice Broadcast Service (VBS) and Voice Group Call Service (VGCS) were defined for this purpose.