Presently, most residential and small business telephone subscribers receive service (i.e., dial tone) from a Local Exchange Carrier, typically via a pair of wires extending between the subscriber's residence or business and a local loop, either a central office, or an intermediate facility, such as a subscriber loop carrier.  The wire pair (often referred to as a "line") running to the subscriber's premises not only carry voice and/or data, but also carry a constant voltage to power the subscriber's station set.  Virtually all Local Exchange Carriers maintain extensive battery plants and/or auxiliary power generation equipment for maintaining the voltage on the subscriber's line in the event of a power failure.  For that reason, local telephone service often continues to operate notwithstanding the lack of electrical power to the subscriber's premises.  Many subscribers have grown accustomed to the high degree of reliability of traditional telecommunication service furnished by their Local Exchange Carrier. 
The deployment of bi-directional cable television networks now affords the opportunity for subscribers served by such networks to obtain telecommunications services from their cable television service provider rather than their Local Exchange Carrier.  Indeed, the high bandwidth afforded by the coaxial cable deployed by cable television service providers in their cable plant allows such service providers to offer a variety of enhanced telecommunications services not all of which are available to all subscribers served by a Local Exchange Carrier. 
Presently, telecommunication service over a cable television transmission path requires certain equipment at the subscriber's premises, such as a multiplexer, to multiplex the telecommunications onto and off the transmission path.  For the most part, such equipment requires external power that is obtained from the AC electrical service at the subscriber's premises.  Unfortunately, such equipment will likely become inoperative in case of a power failure, resulting in a loss of telecommunications service.  Moreover, even if the equipment at the subscriber premises for providing telecommunications over the cable television transmission path remains operative, other equipment in the cable television plant, such as trunk and line amplifiers, that lack standby power, may become inoperative in the event of a power failure, thus interrupting service. 
Despite the potential service offerings available with telecommunications over cable television, subscribers have declined such service in favor of the more reliable telecommunication service offered by their Local Exchange Carrier.  Thus, there is a need for a technique for providing uninterrupted telephony service that takes advantage of the benefits afforded by alternative mediums, such as cable television or the like, yet affords high reliability.