Group 4 protocol

Updated: 11/12/2023 by Computer Hope
Brother fax machine.

The Group 4 protocol is the international standard devised by ITU (International Telecommunication Union) for sending and receiving faxes over ISDN (Integrated Services Digital Network) lines.

What sets Group 4 apart from Groups 1-3 is that it employs digital transmission for fax images, instead of 1-3's analog methods, which operate over telephone lines. Consequently, faxes sent using Group 4 protocol over digital lines can have better image quality. Group 4 protocols are designed for transmission between 64 kbps systems and support image resolutions of up to 400 DPI (dots per inch).

How many protocols are there in group 4?

Below are the following protocols that make up Group 4 with links to the PDF (Portable Document Format) recommendations from ITU.

Fax, Group 3 protocol, Hardware terms, ISDN, ITU, Telephone