Following are some photos taken of pages of a Desk-Fax technical manual. Thanks to Jeff Hook for providing these.

Network block diagram showing the relationship of the Desk-Fax units to central-office equipment.

A page detailing the transmission protocol. The page shown is for transmitting a fax from the central office to a Desk-Fax.

Text describing a test table for directly interconnecting two Desk-Faxes.

Diagram of the test table described in the above text.