Protocols Fax machines have long been in use, but recently modems with fax capability have begun to take their place.
Fax modems are considerably smaller and cheaper than fax machines.
The original fax machines were classified as Group 1. Group 1 fax machines were very slow, taking 6 minutes to send a single page. In the late 70's, these were replaced by Group 2 fax machines. These machines converted the image into digital signals, which were then transmitted by modem. These digital signals were much more reliable, as they were affected much less by line noise than the analog signals sent by Group 1 machines.