Federal Telephone System. Security Of: Note by Secy.

as on the green (or red) system as only the federal exchange is involved. (ii) If a call is made between a federal instrument and an instrument on the ordinary black system (as may easily happen if a caller on a federal instrument asks, not for a federal number but for say "the Admiralty" and then for a person in the Admiralty, in which case his connection would be made through the ordinary Admiralty Black exchange) this security will of course be very much reduced. 3. Mr. Gracie made the important point that in the War Office there are no separate federal telephone instruments, but that if anyone at the War Office wishes to use the federal system this can only be done via their ordinary black telephone and thence via a tie line to the federal exchange.