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Old 7th Sep 2018, 12:34 pm   #10
OscarFoxtrot
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Join Date: Apr 2011
Location: Edinburgh, UK.
Posts: 805
Default Re: Dialling before STD

Toll calls were connected on demand, trunk calls were booked and the operator rung you back.

Due to increasing demands for trunk calls from London and the associated delays in connecting them, calls to exchanges adjacent to the London director area were transferred to a new Toll exchange opened on 17 September 1921. Calls to toll area exchanges were connected on-demand whilst the originating subscriber waited thus improving service and reducing operator costs.

The London Toll Area boundary was extended in 1923 and again in 1928, so that eventually Southampton, Portsmouth, Reading, Bedford, Colchester and the whole of Kent and Sussex were included. The system was later introduced to other large cities and remained in use until the late 1950s when, with the advent of Subscriber Trunk Dialling (STD), Toll was eventually phased out.

In the London telephone area, calls to subscribers who were not serviced by Director telephone systems within local call-charging range of the London Director exchange area were carried by tandem exchange Toll A: a subscriber would dial a prefix code, typically two letters plus zero, one or two figures (e.g. DA, EP5, LK85) followed by the number of the other subscriber on the fringe non-director exchange. To avoid confusion, three-letter dialling codes were not used for calls from the director area to the fringe area, even if they corresponded to the same holes in the dial (e.g. the Hoddesdon and Mogador codes were HO3 and MO4 respectively).

https://www.btplc.com/Thegroup/BTsHi...o1968/1921.htm
and
https://en.wikipedia.org/wiki/Trunk_...toll_telephony
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