Abstract: A system for accessing a plurality of telephone wires which are two-wire, four-wire and six-wire circuits, including a common access test bus, a common control bus, a plurality of access shelves for connecting the circuits to the common access test bus, in which each access shelf is individually selectively controllable to connect the circuits to the common access test bus in response to control signals on the common control bus, and a test controller having a programmable data processor for selectively generating the control signals to individually control any one of the access shelves.

Abstract: A system for accessing a plurality of telephone wires which are two-wire, four-wire and six-wire circuits, including a common access test bus, a common control bus, a plurality of access shelves for connecting the circuits to the common access test bus, in which each access shelf is individually selectively controllable to connect the circuits to the common access test bus in response to control signals on the common control bus, and a test controller having a programmable data processor for selectively generating the control signals to individually control any one of the access shelves.

Abstract: A measurement method and apparatus for determining the duration of a current signaling pulse in a telephone circuit, without breaking or interrupting the circuit, through observing a voltage waveform across the circuit, even though the voltage waveform is distorted by characteristics of the circuit and components attached to it. According to one embodiment, the derivative of the voltage pulse is electronically taken to identify the leading and trailing edges of the current pulse, a pedestal voltage added to it and then its transitions sensed. According to another embodiment, a high impedance technique is utilized which does not impair service along the communication circuit being measured, this technique sensing transitions of the voltage waveform and processing the signal to avoid the effects of any zero crossings that occur during the pulse as a result of high amplitude ringing or relay contact bounce.