Circuit to provide backup telephone service for a multiple service access system using a twisted pair

Abstract

A system for providing a life line safety connection from a subscriber telephone in a multiple band communication network for customer premise equipment is disclosed. Whenever a failure is detected in any of the systems or components an alternate route through line cards that bypasses digital multiplexing circuits enables a subscriber telephone such as an analog telephone to communicate through plain old telephone lines to outside networks. In some embodiments switches are automatically triggered to activate the life line safety connection. Other embodiments use a selected frequency band for providing the life line safety connection. Failure in external network interfaces as well as in a subscriber server or in customer premise devices can be effectively bypassed by practicing these life line safety connection techniques.