A presence of a facsimile transmission tone generated by a calling party within
a call is sensed for within a public telephone network before the call has been
routed to a called party. If the facsimile transmission tone is present in the
call, the telephone network denies completion of the call to the telephone line
of the called party. If the call is absent the facsimile transmission tone, a telephone
network switch is instructed to complete the call to the telephone line of the
called party.