Physical Properties of Materials

Physical Properties of Materials

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 edition. Excerpt: ...is thereby stopped only during a silent period. If the ringing is done manually the B operator is informed by the ringing signal when the called party answers, but if machineringing equipment is used the connection is completed as far as the B operator is concerned when she has depressed the proper ringing key. In all cases when the called party answers the supervisory signal associated with the A operator's calling cord is extinguished just as it is for a nontrunked call. The A operator either makes sure that the desired connection is completed or reports to the calling party that the called party does not answer. A-B trunk operation is nearly always used between large central offices in the same local service area and very frequently for intraoffice calls in very large central offices of a multiofiice area where the percentage of calls which do not have to be trunked is so small that the expense of providing multiple jacks before A operators is not warranted. In this case the calls which are local to such an office are also trunked. Tandem B Operator's Position Equipment.--In large multioffice local areas where each office must have trunk connection with each other ofice it is frequently found more economical to operate A-B trunks in series or in tandem, as it is called, than to provide each oflice with direct trunks to each other office. Calls to groups of offices are then routed through one of the ofiices which is centrally located with respect to the others in the group, and that oflice is provided with B operator's position equipment, which is arranged for connecting incoming call-circuit trunks, known as tandem trunks, with outgoing call-circuit trunks, known as completing trunks. Such a B operator's position is known as a...show more

Product details

  • Paperback | 238 pages
  • 189 x 246 x 13mm | 431g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236960246
  • 9781236960245