GB1247334A - Call regulator for a telecommunication switchboard - Google Patents

Abstract

1,247,334. Manual exchange systems. POST OFFICE. 21 Nov., 1968 [31 Aug., 1967], No. 39915/67. Heading H4K. At an operator's position, incoming calls are formed into a queue until a first predetermined number of calls are waiting whereafter further calls are prevented from joining the queue until the number of calls waiting therein has fallen to a second predetermined number. The disallowed calls may be diverted to a supervisor or to an announcement and/or recording machine or they may receive busy tone. If a call has been waiting an excessive amount of time, further entry to the queue-even though it is not full-can be prevented. A pair of contact ammeters CAA, CAB (Fig. 2) are connected to the lamp indicator-calling relay LR circuit of each incoming circuit. When the second (equal or lower) predetermined number of calls are waiting, the current through CAB is sufficient to close its contacts whereby relay RLB (Fig. 1) comes up. When the first predetermined number of calls are waiting, ammeter CAA's contacts close to energize RLA which then locks up. RLA brings up RLP in order to earth the P-wires of the other incoming circuits at this position. The appearance of the earth causes a selector to step on to another level where appropriate action is taken. When the number of calls waiting falls to the second predetermined number, CAB's contacts open to release RLB, RLA, RLP whereby new calls can be directed to this position. Ammeter CAB may be connected in place of contacts RLB1 thereby dispensing with relay RLB.