Line interface unit for caller-controlled receipt and delivery of voice messages

摘要: A line interface unit for controlling receipt and delivery of voice messages over a telephone system having message facility connectable to at least one calling station called via central office. The comprises first switch connected the in tip ring lines second office lines, switches positions wherein said signals on are directly between when each is position. In operation, control circuit responds detection busy/no answer condition switching from its position connect speech issuing prompt. After prompt issued, DTMF signal or additional coinage speed-dial dialing facility. then their back