GSM-R intercoms are used in the railway network. They are used for operational communication, i.e., communication between mobile and stationary participants in railway operations. A local station telephone connection is established, which can be extended to the line if necessary, as a connection to the responsible operating center, e.g., from the track area to the responsible dispatcher. This does not involve any of the functionalities required for line telephone connections (e.g., emergency calls on the line). They can be used on the railway network (GSM-R) or via a SIM card from a locally available operator (GSM).