When a facsimile transmission is carried over a packet network such as the Internet that disallows the use of non-standard facilities with which the facsimile terminals may be provided, a communication apparatus that mediates the transmission blocks signals requesting the use of non-standard facilities, but replaces the blocked signals with modified data not requesting the use of such facilities. Consequently, even if a facsimile terminal sends a lengthy non-standard facilities signal, the facsimile terminal with which it is communicating will not time out due to non-reception of data, and the facsimile transmission can be completed using standard facilities.