A communication system includes a transmitting apparatus and a receiving apparatus that communicates with the transmitting apparatus over a telephone line. The transmitting apparatus includes a first facsimile transmitting section, a first voice-information transmitting section that transmits first voice information that is voice information on a first user, and a first control section. The receiving apparatus includes a second facsimile receiving section, a second voice-information communication section that receives the first voice information, and a second control section. The second control section permits or rejects reception of the image information from the transmitting apparatus via the second facsimile receiving section based on a result of authentication of the first user performed based on the received first voice information and second voice information on a user who is permitted in advance to use the receiving apparatus.