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

Abstract

A subscriber link to a central office which employs data compression, forward error correction, and advanced modulation techniques and to connect subscribers to multiple communications networks to provide an array of services. A device provides normal telephone service in the event of an equipment failure. At the subscriber end, a server called an intelligent services director (ISD) provides multiple independent connections for telephones which ordinarily connect to multiple access virtual circuits generated on the subscriber link over a twisted pair. A device called a facilities management platform (FMP) at the central office end of the link, among other things, provides interfacing of the subscriber link to various networks including a digital subscriber loop (DLC) and packet switched networks. Ordinarily telephones connected to the ISD require power and correctly functioning modems and controllers in the ISD and the FMP to have access to the outside world. A fail-safe mechanism, however allows at least one chosen phone to function in the event of a failure. The chosen phone must be capable of pulse or DTMF dialing. The connection through which it operate can be switched directly to the twisted pair media connecting to the FMP. At the FMP, the twisted pair is switched to tie the connection directly to a line card of the DLC. Alternatively, the ISD contains an interface to a specialized phone designed for the ISD environment. The interface provides the appearance to the DLC of a regular POT

We claim:  
     
         1 . In a broadband communication network, a method for providing fail-safe telephone connectivity between a subscriber server including a telephone and a telephone network facility, comprising switching a connection from the telephone to a broadband communication network interface directly to a telephone network facility line when a fault is detected in the broadband communication network.  
     
     
         2 . The method according to  claim 1 , wherein detecting a fault in the broadband communication network comprises listening for a status signal from the broadband communication network at the subscriber server and determining that a network fault exists if the status signal is not received in a threshold period of time.  
     
     
         3 . The method according to  claim 1 , wherein detecting a fault in the broadband communication network comprises listening, at a location in the broadband communication network, for a status signal from the subscriber server and determining that a network fault exists if the status signal is not received in a threshold period of time.  
     
     
         4 . In a broadband communication network, a method for providing fail-safe telephone connectivity between an analog subscriber telephone and a telephone network facility, comprising connecting the analog subscriber telephone to the telephone network facility through a connection different from a connection between a subscriber server and the broadband communication network.  
     
     
         5 . In a broadband communication network including a telephone network facility, a method of providing fail-safe telephone connectivity between a subscriber and the broadband communication network comprising: 
 providing a primary digital telephone connection via a subscriber server connected to the broadband communication network; and    providing a backup analog telephone connection directly to the telephone network facility bypassing the subscriber server when a fault in the subscriber server occurs.    
     
     
         6 . The method according to  claim 5 , wherein the primary digital telephone connection comprises connecting a modem at the subscriber server to the telephone network facility.  
     
     
         7 . The method according to  claim 6 , wherein providing the backup analog telephone connection comprises connecting an analog telephone to the telephone network facility on the same line connecting the subscriber server and the telephone network facility, the analog telephone using a different frequency spectrum than the digital telephone.  
     
     
         8 . The method according to  claim 5 , further comprising detecting fault in the subscriber server by identifying a failed polling process.  
     
     
         9 . The method according to  claim 5 , wherein the fault in the subscriber server is a power failure at the subscriber server.  
     
     
         10 . The method according to  claim 6 , wherein the fault in the subscriber server is a modem failure.