Abstract: Ground terminal serving a number of individual telephone lines in a local region converts their signals to an intermediate frequency. If called station is in remote region linked by relay satellite, intermediate frequency is selected in band dedicated to conversion to (or from) satellite frequency band by frequency converters. If called station is in local region, intermediate frequency is selected in a different band dedicated to local traffic. Frequency-selective filters automatically route signals in satellite-dedicated intermediate frequency band to (or from) satellite-linked channels, and signals in local-traffic-dedicated intermediate frequency band to a channel common to local lines, eliminating need for switching between two kinds of channels. Two local-region telephone lines may be linked by appropriate intermediate-frequency assignments, thus performing function equivalent to ordinary telephone exchange.