Signaling Systems for Control of Telephone Switching

Abstract

Telephone signaling is basically a matter of transferring information between machines, and between humans and machines. The techniques developed to accomplish this have evolved over the years in step with advances in the total telephone art. The history of this evolution is traced, starting from the early simple manual switchboard days to the present Direct Distance Dialing era. The effect of the increasing sophistication in automatic switching and transmission systems and their influence on signaling principles are discussed. Emphasis is given to the signaling systems used between central offices of the nationwide telephone network and the influence on such systems of the characteristics of switching systems and their information requirements, the transmission media and the compatibility problem. A review is made of the forms and characteristics of some of the interoffice signaling systems presently in use. In addition, the problem of signaling between Bell System and overseas telephone systems is reviewed with reference to differing information requirements, signaling techniques and new transmission media. Finally, some speculation is made on the future trends of telephone signaling systems.

Performance evaluation of dialed number recorders

“…Frequency Resolution: 0.1 Hz (10 Hz to 1 MHz, AC coupled) 3 In order to describe the systems and tests described in this report adequately, commercial equipment and instruments are identified by manufacturer's name and/or model number.…”

“…During the testing the dialed-pulse speed discrimination circuits of the DNR were checked for their ability to detect both the rotary dial pulse repetition (8 through 12 pps) and automatic dial pulse repetition ranges (8 through 25 pps) [1,3], although an attempt was not made to evaluate the DNR UUT throughout the allowed range of pulse repetition rates. Since the technology for dialing is moving almost exclusively towards pulsed tone methods (DTMF, MF, etc.…”

Postdigital Aesthetics

“…According to Bell System, the New York Metropolitan area of the 1920s already had 1,400,000 telephones and about 158 central offices, with operators serving up to 10,000 lines from one office (Craft, Morehouse and Charlesworth 1923, 56). Forty years later, more than 15 million telephones had 'access to nationwide dialing' (Breen andDahlbom 1960, 1382).…”

A modeling and simulation methodology for analyzing ATM network vulnerabilities

“…No additional bandwidth was required, and the signaling could easily be moved across available speech channels. However, clever users soon discovered mechanisms to gain access to the switch by sending special characters during a conversation session, and they could dial long-distance calls without being detected [12,13]. This cost Ma Bell untold dollars [14].…”