There is still another class of manual switchboards called the toll board of which it will be necessary to treat. Telephone calls made by one person for another within the limits of the same exchange district are usually charged for either by a flat rate per month, or by a certain charge for each call. This is usually regardless of the duration of the conversation following the call. On the other hand, where a call is made by one party for another outside of the limits of the exchange district and, therefore, in some other exchange district, a charge is usually made, based on the time that the connecting long-distance line is employed. Such calls and their ensuing conversations are charged for at a very much higher rate than the purely local calls, this rate depending on the distance between the stations involved. The making up of connections between a long-distance and a local line is usually done by means of operators other than those employed in handling the local calls, who work either by means of special equipment located on the local board, or by means of a separate board. Such equipments for handling long-distance or toll traffic are commonly termed toll switchboards.
They differ from local boards (a) in that they are arranged for a very much smaller number of lines; (b) in that they have facilities by which the toll operator may make up the connections with a minimum amount of labor on the part of the assisting local operators; and (c) in that they have facilities for recording the identification of the parties and timing the conversations taking place over the toll lines, so that the proper charge may be made to the proper subscriber.
[CHAPTER XXI]
THE SIMPLE MAGNETO SWITCHBOARD
Definitions. As already stated those switchboards which are adapted to work in conjunction with magneto telephones are called magneto switchboards. The signals on such switchboards are electromagnetic devices capable of responding to the currents of the magneto generators at the subscribers' stations. Since, as a rule, magneto telephones are equipped with local batteries, it follows that the magneto switchboard does not need to be arranged for supplying the subscribers' stations with talking current. This fact is accountable for magneto switchboards often being referred to as local-battery switchboards, in contradistinction to common-battery switchboards which are equipped so as to supply the connected subscribers' stations with talking current.
The term simple as applied in the headings of this and the next chapter, is employed to designate switchboards adapted for so small a number of lines that they may be served by a single or a very small group of operators; each line is provided with but a single connection terminal and all of them, without special provision, are placed directly within the reach of the operator, or operators if there are more than one. This distinction will be more apparent under the discussion of transfer and multiple switchboards.
Mode of Operation. The cycle of operation of any simple manual switchboard may be briefly outlined as follows: The subscriber desiring a connection transmits a signal to the central office, the operator seeing the signal makes connection with the calling line and places herself in telephonic communication with the calling subscriber to receive his orders; the operator then completes the connection with the line of the called subscriber and sends ringing current out on that line so as to ring the bell of that subscriber; the two subscribers then converse over the connected lines and when the conversation is finished either one or both of them may send a signal to the central office for disconnection, this signal being called a clearing-out signal; upon receipt of the clearing-out signal, the operator disconnects the two lines and restores all of the central-office apparatus involved in the connection to its normal position.
Component Parts. Before considering further the operation of manual switchboards it will be well to refer briefly to the component pieces of apparatus which go to make up a switchboard.