A method for preventing in device coexistence (IDC) interference of a communications apparatus including at least a first radio module providing a first wireless communications service in a first wireless network in compliance with a first protocol and a second radio module providing a second wireless communications service in a second wireless network in compliance with a second protocol, the method includes: determining whether a protection scheme for preventing IDC interference is to be performed; determining a predetermined time to activate the protection scheme when the protection scheme is determined to be performed; and transmitting a predetermined message to the second wireless network at the predetermined time to activate the protection scheme.