An interface system of information - called connecting a line circuit PC and a telephone apparatus.Process for discrimination between current to the front and back in a circuit of telephone link.The interface of information - called connecting a line circuit PC or PABX and a telephone apparatus; apparatus for determining the polarity of a voltage fed externally input, VI,

摘要

A tip-ring interface that utilizes a single detector to detect ringing, forward loop current, and reverse loop current. In one embodiment, forward or reverse battery state may be detected when on-hook.