NATIONAL TELEPHONE COMPANY
Pattern No. B90
Comprises - Granular Carbon Transmitter, Receiver (Double Pole), Cord Key, 5-way Plug and 5-way
This is differentially and is for use in connection with special multiple Switchboard working, other same remarks apply as in the case of Pattern No. B80.
Was B18 in the 1903 Catalogue.
Last revised: November 11, 2023