There is a need to provide a technique of accurately detecting an identification signal representing that the partner performs facsimile communication, by using an appropriate detection filter in accordance with the operation mode in a facsimile apparatus. Based on whether the FAX/TEL mode (first mode) or the TEL answering mode (second mode) is set as the operation mode, a facsimile apparatus according to this invention determines whether a band-pass filter and band-reject filter are to be used. The facsimile apparatus detects a CNG based on the signal detection result using the determined filter.