Apparatus for detecting an off-hook condition of a telephone line

摘要

Apparatus for detecting an off-hook condition of a telephone line comprising : a telephone data set coupled to the telephone line ; means, coupled to the telephone line, for measuring an initial value indicative of an off-hook electrical characteristic of said telephone line ; means coupled to the telephone line, for measuring an average value of an electrical characteristic of said telephone line at a predetermined time ; means for comparing said initial value and said average value ; and means, responsive to said comparison, for causing said telephone data set to be established in an off-hook condition if said comparison differs by a predetermined amount. <IMAGE>