PURPOSE: To select plural devices, which are connected to one line, by judging whether the number of calling tones arrives at the number of stored calling tone and changing the number of stored calling tones according to a command signal, which is transmitted after incoming.

CONSTITUTION: When the program of a processor 6 is started, whether the tone is a calling tone or not is judged by a calling tone detecting part 5. In the case of the calling tone, when the number of calling tones arrives at the specified number, the line is closed and a timer is set. In the case of a calling tone changing command until the incoming, the data are stored and after that, the line is disconnected. According to the stored data, the specified number is changed. For example, when the number of calling tones of an automatic answering telephone set 3 is set be three times and the number of calling tones of a remote operation control device 11 is set to four times from a condition, in which the number of the device 11 is set to be twice, according to the stored data, in the case that a calling tone next arrives at an input terminal 1 and an input terminal 2 and the number of calling tones arrives at the three times, the automatic answering telephone set 3 is changed to be incoming.