In a 1957 episode of Perry Mason (aired on MeTV), there was a Western Union Desk Fax on Stella's desk.
Desk Fax was a once popular fax service provided by Western Union, using small desk top machines. They were used to send faxes or telegrams.1952 article describing Desk Fax unit
1969 article describing usage in supermarket chain
P.S. In another episode, a telephone switchboard serving Perry Mason's office was shown as a 507 PBX. This was a desktop cordless small sized unit and was popular in its day. In the 1950s and 1960s, key systems were improved with more capacity and features and the 507 became obsolete.
The 507 is described here: