Fax machines use analog phone lines, which are connected using RJ11 connectors. These are standard telephone connectors with 4 or 6 positions and are used for POTS (Plain Old Telephone Service) lines.
F-type is used for coaxial cables (e.g., TV and cable modems).
RJ45 is used for Ethernet network connections.
SC (Subscriber Connector) is used for fiber optic connections, not analog telephone lines.
# Reference:
CompTIA Network+ N10-009 Official Objectives: 2.4 - Compare and contrast common network connectors.