Group 4 protocol
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.
- T.6 - ITU T.6 recommendation
- T.62 - ITU T.62 recommendation
- T.70 - ITU T.70 recommendation
- T.72 - ITU T.72 recommendation
- T.411 - ITU T.411 recommendation
- T.412 - ITU T.412 recommendation
- T.414 - ITU T.414 recommendation
- T.415 - ITU T.415 recommendation
- T.416 - ITU T.416 recommendation
- T.417 - ITU T.417 recommendation
- T.503 - ITU T.503 recommendation
- T.521 - ITU T.521 recommendation
- T.563 - ITU T.563 recommendation