A method is provided for fax call blocking. The method includes: receiving a first call intended for an end instrument (10) employed by a user; obtaining a telephone number from which the first call originated; comparing the obtained telephone number against a first database (42) to determine if the obtained telephone number matches a blocked telephone number contained in the first database (42); blocking the first call such that the end instrument (10) is not alerted if a match is found between the obtained telephone number and a blocked telephone number, otherwise providing a connection to the end instrument (10) for the first call; monitoring the connection to detect for fax tone; and, entering the obtained telephone number in the database (42) as a blocked telephone number if fax tone is detected.