A facsimile apparatus connected on an ISDN side in a communication network in which the ISDN is connected to a telephone network includes network identifying means for identifying whether an incoming data sending party is an ISDN terminal or a telephone network terminal, CNG signal detecting means for detecting a CNG signal received via a B channel, and changeover means for changing over between automatic reception and manual reception. In a case where the CNG signal is detected, a response is made in a facsimile mode. In a case where the CNG signal is not detected, a response is made in a facsimile mode if automatic reception prevails and in a telephone mode if manual reception prevails. This arrangement eliminates communication failure due to a difference in mode between a calling side and a called side regardless of the network terminal from which a call is received.