A speech freeze-out method in a communication system for transmitting speech information, which is sent from public telephone terminals (1) to a control center (5) through voice channels, from the control center (5) to a base station (8) through time division multiplexing radio frequency channels (6), and from the base station (8) to mobile stations (17) through transponders (13). The freeze-out processing is carried out when the control center (5) feeds the speech information to the time division multiplexing radio frequency channels (6) so that the number of transmission channels from the base station (8) to the transponders (13) is limited within an upper limit value. The control center (5) sequentially detects the presence and absence of a speech spurt in each frame of respective voice channels during each time slot of the time division multiplexing radio frequency channels, counts the number of the channels including the speech spurt, and performs the speech freeze-out processing when the count value exceeds the upper limit value. The number of transmission channels from the base station (8) to the transponders (13) is positively limited within the upper limit value.