(Louis Meulstee’s web site)
Other Fullerphone applications
Hand keying on VF telegraph circuits.
There were occasions when teleprinters were not available, because of failures or for other reasons, and it was desired to work VF telegraph circuits by hand-keyed Morse. Several of the suitable methods applicable to three or six channel VF telegraph systems, as well as S+DX, involved the use of a (slightly modified) Fullerphone without having to modify the VF equipment.
(Reference: Training Memorandum No. 5, pp38-43, Nov. 1943.)
Fullerphones on submarine cable circuits.
It sometimes happened that submarine cables became available when the normal terminal equipment had been rendered unusable or could not be obtained without long delays. Circuits in such cables could be worked with Fullerphones by the methods detailed below.
To make the use of Fullerphones practicable on submarine cables, suitable measures had to be taken to maintain the shape of signals. Good signals at 30 words per minute had been obtained on circuits not greater than 700 miles in length.
(Reference: Training Memorandum No. 5, pp42-43, Nov. 1943.)