A facsimile apparatus is provided with changeover means that makes it possible
to pass signals through or to bypass a coder, which encrypts transmission information,
and a decoder, which decodes encrypted information that has been received. Whether
or not a facsimile apparatus belonging to another party has an encrypting/decoding
processing function is verified by a pre-procedure signal. If the other party's
apparatus possesses an encrypting/decoding processing function, control is performed
in such a manner that encrypting/decoding processing is applied solely to an image
signal and a training-check signal transmitted before transmission/reception of
the image signal, and encrypting/decoding processing is not applied to a procedure
signal which accompanies of the image signal. If the other party's apparatus does
not possess an encrypting/decoding processing function, it is possible to select
between terminating communication and performing facsimile communication without
executing encrypting/decoding processing.
