GEC No. 89
The G.E.C. Muraphone, Cat. No. 89, incorporates all the features and
circuit principles of the Gecophone No. 75, but differs
in that the case has been specially designed to meet the demand for a
wall-mounting instrument. Initially designed for ships in 1937.
Taken from the GEC Private Automatic Telephone Exchanges No. 18/3A (undated)
Last revised: November 12, 2021