A control circuit (1) determines transmission power for a test signal in
accordance with the number of call connections of a radio terminal
call-connected to the apparatus during a loopback test. The determined
transmission power (TSTP) is output to channel circuits (21-2n) used for
the transmission of a loopback test signal. The channel circuits (21-2n)
adjust the transmission power of the test signal on the basis of the
transmission power (TSTP) from the control circuit (1).