Faxing

Faxing is the process of sending scanned documents over telephone networks using fax machines, multifunction printers, or software-based fax clients. A sender’s device scans each page, encodes the image into a standardized format, and transmits it as signals over a telephone line or an IP network. The receiving device decodes the signals and reproduces the document, typically as a printed page or an electronic file such as PDF. Transmission quality varies with line conditions and the chosen resolution.

The traditional workflow relies on ITU-T Group 3 standards for image encoding and ITU-T T.30 for session setup and capability exchange. Group 3 uses compression schemes such as MH, MR, and MMR, with optional error correction. In modern networks, fax over IP can use ITU-T T.38 to send faxes as data packets, enabling interoperability between traditional PSTN fax and IP-based systems or cloud services. Some offices also use online or email-based fax services that route faxes through the internet without a dedicated telephone line.

Equipment and usage have evolved from standalone machines to multifunction devices and cloud-based or email-based workflows. Faxing remains common in certain sectors, including regulated industries, legal, healthcare, and government, where documented transmission and archiving are important. Online fax services provide sending and receiving via web interfaces, email, or mobile apps, often with additional storage and integration options.

Security considerations include that traditional fax transmissions over analog lines are not end-to-end encrypted by default, though some services offer encryption in transit or via VPN. Overall, faxing persists as a complementary method for document transmission alongside more modern digital channels.