Device which reduces central office battery current during modem connections

Abstract

In the occurrence of a data modem establishing a data communication session over a telephone line, a method is disclosed for detecting the modem and subsequently reducing the telephone line current. Initially, when a new telephone call is begun, the line current is set as normal to a current sufficient to power a standard telephone handset. Subsequently, using modulation detection techniques, it is determined whether a modem data session has been initiated on the particular telephone line. If such a session has begun, the normal current level on the telephone line is unnecessary since data modems are locally powered. To minimize wasted power and reduce thermal problems caused by the modem dissipating the excessive current, a reduced current is set on the telephone line. This reduced current is either a predetermined modem current level or a minimum allowable current for the particular telephone line, as calculated within the line interface circuit.

Dependencies are inferred from the claim text.