System to provide lifeline IP telephony service on cable access networks

• US 6,556,562 B1
• Filed: 09/29/1999
• Issued: 04/29/2003
• Est. Priority Date: 09/29/1999
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Weber, Roy Philip, Bhagavath, Vijay K., OʼNeil, Joseph Thomas
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): DO, NHAT Q
• Application Number:
  US09/407,916
• Time in Patent Office: 1,308 Days
• Field of Search: 370/352, 370/356, 370/216, 375/222, 725/111, 725/118, 725/127, 725/128, 725/130
• US Class Current: 370/352
• CPC Class Codes: H04M 19/08 with current supply sources at the substations generating ringing current H04M19/04

Abstract

A cable access network includes a cable trunk amplifier connected over a coaxial cable to A plurality of cable data modems to provide backup power to the cable modem during power outages experienced by either the trunk amplifier or the modems, thereby insuring uninterruptible IP telephone service. The trunk amplifier applies a DC voltage across the conductors of the coaxial cable. An AC/DC power converter and regulator and also a backup battery are sources of power for the DC voltage applied to the coaxial cable. A power outage sensor selectively connects either the AC/DC power converter and regulator or, alternately, the backup battery to the cable, depending on whether there is an outage sensed at the trunk amplifier. Each cable data modem connected to the trunk amplifier is partitioned into IP voice circuits and other circuits not contributing to the IP voice function. The other circuits include, for example, video/audio receiver circuits and IP data transceiver circuits. The IP voice circuits are connected to the subscriber'"'"'s telephone hand set. The cable data modem applies a DC voltage to the IP voice circuits and the subscriber'"'"'s telephone hand set. An AC/DC power converter and regulator in the modem and also the DC voltage from the coaxial cable are sources of power for the DC voltage applied to the IP voice circuits. A power outage sensor selectively connects the IP voice circuits to either the AC/DC power converter and regulator in the modem or, alternately, the DC voltage from the coaxial cable, depending on whether there is an outage sensed at the cable data modem. The other circuits such as the video/audio receiver circuits and IP data transceiver circuits are powered only by the AC/DC power converter and regulator in the cable data modem. In this manner, if there is a general power outage affecting both the trunk amplifier and many of the cable data modems connected to it, the power to be supplied by the backup battery at the trunk amplifier is only required to power the IP voice circuits and the subscriber'"'"'s telephone hand set.

Claims

1. A cable access network, comprising:

a cable trunk amplifier connected over a coaxial cable to A plurality of cable data modems;

a main power source and a backup power source in said cable trunk amplifier for applying a DC voltage to the coaxial cable;

a power outage sensor in said cable trunk amplifier that selectively connects either the main power source or the backup power source to the cable, depending on whether there is an outage sensed at the trunk amplifier;

at least one cable data modem connected to the trunk amplifier, said modem being partitioned into IP voice circuits and other circuits not contributing to an IP voice function;

a local main power source in the modem and the DC voltage from the coaxial cable for providing sources of power for the IP voice circuits; and

a local power outage sensor in the modem for selectively connecting the IP voice circuits to either the local main power source or the DC voltage from the coaxial cable, depending on whether there is an outage sensed at the cable data modem.

2. The cable access network of claim 1, which further comprises:

said IP voice circuits connected to a subscriber'"'"'s telephone hand set which is powered by the cable data modem.

3. The cable access network of claim 1, which further comprises:

said other circuits including video/audio receiver circuits and IP data transceiver circuits.