Toll Switchboard No. 3

lamps replaced the old type drops and the subscriber was given means for calling the toll operator on a toll connection by operating the switchhook instead of ringing. Up to this time the toll operators were located at the local switchboard and had direct access to the subscriber's line, but with the growth of toll and local traffic, it was no longer economical to place the toll operators at the local board. This led to the development of a separate toll switchboard called the No. 1 board, which had access to the subscriber's line over switching trunks between the toll and local boards. For many years the No. 1 switchboard filled the needs of the time but with the expansion of the toll service and the growth of machine switching local service, it became evident that new arrangements were desirable. The No. 3 toll switchboard was developed to meet the new requirements and it has the following advantages as new installations are required. (a) Reduction in apparatus, resulting in equipment economies. (.b) Improved maintenance arrangements. (c) More readily adapted to modifications required by new operating methods. In discussing the features of the No. 3 board, frequent comparisons will be made with the No. 1 switchboard to set forth the changes which have been made in the design of the new circuits. M A I N FEATURES early days of the toll consisted a the line and a drop or ringer in the cord. INofthemagnetic drop intelephonysignaling signaling apparatusrelaysWith the advent of common battery in the local plant, and Cord Simplified by Locating Supervisory Relays in Line and Trunk Circuits The cord circuit of the No.