Method of and apparatus for providing multiple independent voice telephone line circuits using and including a packet voice device

A system and method overlay of advanced digital technology onto the installed feeder and distribution cable portion of the outside plant to obtain additional voice circuits. Interface equipment proximate existing drop wire interface points converts digitized voice circuits back to analog signaling together with appropriate POTS signaling and power connections. The interface equipment is centrally powered along with other portions of the outside plant so that operation is independent of customer and commercial power sources. Power may be provided by batteries located at the associated central office or by locally provisioned, non-interruptible, battery-backed-up power sources. The existing switched telephone network includes central offices connected by interoffice facility trunks, each central office providing service to nearby subscribers connected by local loop facilities. These local loop facilities include a feeder/distribution system connecting the central offices to respective serving area interfaces and local drops connecting respective subscriber to the serving area interfaces. The capabilities of the feeder/distribution facilities are enhanced and expanded to accommodate additional subscribers by (re) configuring the feeder/distribution system to provide multiple digital subscriber lines between the central offices and the serving area interfaces or terminals using respective digital subscriber line circuits. The digital subscriber line circuits are terminated at respective Packet Voice Devices located at remote DSLAM terminals serving SAIs or mounted at serving terminals; and subscriber lines are assigned to individual channels of each of the digital subscriber line circuits.

BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIG. 1, a central office (CO) 100 includes a circuit switch 110 complying with conventional voice switch technical and generic requirements, such as TR57/TR08/GR-303, the Lucent Technologies 5E, or Nortel DMS 100 switches. Conventionally, circuit switch 110 includes line cards providing service to multiple DS0 type lines through a main distribution frame (MDF) 120 , part of the distribution facilities supporting circuit switch 110 . MDF 120 interfaces the switching facilities with the outside plant. Thus, MDF 120 terminates typically hundreds or thousands of twisted pair circuits connecting multiple serving area interfaces (SAI) 260 s of the outside plant. Although only one SAI 260 is shown, typically one SAI provides service for 300 to 1200 lines and is therefore located in respective neighborhoods of the area served by CO 100 . The SAI is a cross-connect box connecting an F1 or main feed cable 250 to multiple F2 or copper distribution cables 270 that may be located on utility poles above ground, buried below ground, or housed in a suitable panel box such as in an apartment building. The distribution cables 270 connect to terminals 280 near individual customer premises by respective drop wires 290 a and 290 b and network interface devices (NIDs) 292 a and 292 b . As shown, each of the customer premises is provided with two voice telephone lines, one dedicated to a telephone set, the other shared between a conventional telephone and a data modem and associated computer terminal. A Digital Loop Carrier/Next Generation Digital Loop Carrier (DLC/NGDLC) system provides a second architecture for supporting switched voice circuits. Circuit switch 110 connects to digital signal cross connect (DSX) 130 on an appropriate number of digital signal i.e., (DS1) connections. In turn, DSX 130 is connected to ADM/COT 140 which combines the DS1s into a DS3 or OC3 connection to fiber terminating equipment (FTE) 320 via fiber distribution frame (FDF) 150 . FTE 320 is located at a remote site such as a controlled environmental vault (CEV) 300 . FTE 320 connects the DS 3 /OC 3 output from ADMICOT 140 to DLC/NGDLC system 310 which operates to interface the multiplexed optical traffic to individual twisted copper pairs 350 connecting to SAI 360 provisioned in the neighborhood or locality served by the respective telephone lines. SAI 360 is, in turn, connected by F2 copper distribution cables 370 (e.g., copper cables and twisted pairs) to appropriate local terminal devices 380 located near the individual customer premises. Terminals 380 are connected by respective drop wires 390 A and 390 B and NIDs 392 A and 392 B to respective customer premises 394 A and 394 B. A third architecture for providing additional voice telephone lines is based on digital subscriber line (DSL) technology. Circuit switch 110 is connected to Digital Signal Cross-connect (DSX) 160 providing connectivity to next generation network (NGN) 170 . NGN 170 may include, for example, a switched voiced gateway (SVG) 172 , A synchronous Transfer Mode (ATM) switch 174 and/or Next. Generation Switch (NGS) 176 and similar digital and packet based switching and routing systems. Thus, NGN 170 connects via various optical carrier networks and digital protocols to ADM 180 and appropriate interoffice facilities (IOF) 190 . NGN 170 also provides OC3c connectivity via FDF 150 to FTE 410 and digital subscriber line access multiplexer (DSLAM) 420 , both located at a remote location such as CEV 400 . DSLAM 420 serves as a packet concentrator, delivering traffic from multiple packet voice devices (PVDs) mounted in PVD shelf 430 and multiple customers over the high-speed OC3c link to NGN 170 and circuit switch 110 . DSLAMS and associated IADs (PVDs) may be obtained from commercial sources such as, for example, CopperCom, Inc., Cisco Systems, Inc. XEL Communications, Inc., Jetstream Communications, Inc., Alcatel, Copper Mountain, Lucent, Paradyne, and others. Each PVD card of PVD shelf 430 will support up to 48 individual telephone Circuits or more over corresponding twisted pair copper telephone lines. Thus, PVD shelf 430 may support the typical 300-1200 lines handled by SAI 460 , providing service via smaller F2 copper distribution cables 470 to terminals 480 near customer premises 494 a and 494 b . In effect, DSLAM 420 in combination with PVD shelf 430 provide a “back door” access to circuit switch 110 via NGN 170 so that additional voice grade telephone service over conventional plain old telephone service (POTS) lines may be provided to support customer requirements and to extend the useful life of the copper plant and switching equipment. Power to DLC/NGDLC and DSLAM systems in CEV 400 is provided by commercial AC power to rectifiers and batteries which provide non-interuptable battery back-up supply to the systems in the event of a commercial power outage. FIG. 2 is a block diagram of a switch telephone network for providing voice-only POTS telephone lines to a plurality of subscribers as a second line, primary service continuing to be provided using conventional POTS circuit cards and equipment. Thus, a “front door” connection to circuit switch 110 is provided by conventional POTS circuit cards providing respective DS0s on twisted pair at main distribution frame (MDF) 120 . MFD 120 interfaces the switching facilities with the outside plant. Hundreds or thousands of twisted pair circuits connect multiple SAIs 260 for further distribution via an F1 or multiple F2 copper distribution cables to terminals 291 located in the general vicinity of groups of subscribers. As shown in FIG. 2 , terminal 291 is co-located with a remote PVD 293 on a utility pole 282 . Of course, although the terminal 291 and PVD 293 are shown in an above-ground environment, other facilities including buried pedestals or building terminals may be used instead. As will be explained, PVD 293 provides second line service to subscribers at residences 294 a - 294 f using a “back door” connection and access to circuit switch 110 to expand the POTS capabilities of the switching facilities. Referring to FIG. 2 of the drawings, CO 100 includes DSLAM 142 connected to NGN 170 for providing a back door access to circuit switch 110 via DSX 160 . DSLAM 142 is connected through DSL testing and maintenance equipment 142 . Thus, the DSL circuits from DSLAM 142 are then routed to a power/line shelf 152 which provides appropriate DC power for remote equipment including utility pole mounted PVD 293 via MDF 120 and intermediate SAI 260 . Power/line shelf 152 thus provides power and battery backup for remote equipment to ensure uninterrupted POTS service over DSL even when local power is out. PVD 293 , mounted on utility pole 282 in the vicinity of customer premises 294 a - 294 f (powered by DC power provided by power/line shelf 152 ) functions to convert the DSL channels into standard POTS signaling to be provided over local drops to respective network interface devices (NIDs) 292 a - 292 f at the respective customer premises. At each of the customer premises 294 a - 294 f , a primary telephone is supported by standard copper circuit based POTS while a second telephone line including a second telephone and a modem and computer terminal are supported by the DSL provisioned circuits. In case of loss of power, all required circuitry and systems are powered by the CO including, for example, in the case of the copper based POTS circuits, battery and ringing, and in the case of DSL-based systems, power to PVD 293 . In addition, PVD 293 provides standard POTS loop current and signaling to the associated local drops supporting customer premises 294 a - 294 f . FIG. 3 is a block diagram of still an alternate configuration for supplying second line voice grade service to customer premises 294 a - 294 f using DSL to expand the capability of circuit switch 110 . Thus, as described in connection with FIG. 2 , DSLAM 142 provides a back door into switch 110 . However, unlike the configuration of FIG. 2 , all PVDs are installed at CO 100 in PVD shelf 152 to convert the DSL into standard POTS lines. All telephone lines egressing CO 100 via MDF 120 appear to the distribution system as standard POTS, while a portion represented by the dotted line are, in actuality, converted from DSL-based circuits. This provides additional capability for circuit switch 110 which could not otherwise be supported by provisioning of additional POTS line cards to provide the required DSOs, particularly in the second line situation. Since this second line capability is supplied at the CO as standard copper-based POTS, a second terminal 295 is included on pole 282 to provide a second grouping of drops for the associated customer premises 294 a - 294 f . FIG. 4 illustrates another configuration using both Digital Loop Carrier/Next Generation Digital Loop Carrier (DLC)/NGDLC to extend the local loop into the field and DSL to add additional line capability, not otherwise supported by switch 110 of CO 100 . Thus, a conventional DLC/NGDLC interface to switch 110 includes a DSX 130 for connecting multiple DS1s from switch 110 to ADM/COT 140 , which are then routed to FDF 154 . In turn, these DS1s are supplied to a DLC/NGDLC system 310 via fiber terminating equipment 320 at, for example, a CEV 300 . DLC/NGDLC 310 converts the digital voice channels into standard POTS, which is then distributed via SAI 360 to terminal 291 and customer premises 294 a - 294 f . Referring to FIG. 4 , second line capability is again supported by DSL, a remote DSLAM 420 included in a remote location such as CEV 300 . DSLAM 420 interfaces via FTE 410 and FDF 154 to NGN 170 as previously described. DSL related power and test equipment including power/line shelf 430 and 440 are included in the CEV together with the remote DSLAM equipment 420 . DSL circuits are then routed through SAI 360 to PVD 293 mounted on utility pole 290 a via F2 cable 460 . POTS lines are then distributed to customers 294 a - 294 f via drop wires to NIDs 292 a - 292 f . Referring to configuration of FIG. 5 , the DSLAM equipment is located in CEV 300 together with DLC/NGDLC 310 similar to FIG. 4 . Instead of a power/line shelf in FIG. 4 to support PVD 293 on utility pole 290 a , FIG. 5 interfaces DSLAM 420 to PVD shelf 430 to convert DSL circuits to POTS lines for distribution. Power to DLC/NGDLC and DSLAMs may be supplied by batteries or some other non-interruptible power source so that second line capability is maintained even in a power outage situation, a feature considered important to standard POTS. Respective DSL channels carrying POTS lines are then transported to SAI 360 where they are cross-connected to distribution cable 460 and transported to new terminal 295 at utility pole 282 . Distribution to respective customer premises 294 a - 294 f is as previously described via two pairs of twisted copper wires connecting respective customer NIDS 292 a - 292 f to terminal 291 and new terminal 295 . FIG. 6 shows a configuration of remote DSLAMS for, this case, providing a full 1200 POTS lines. Because each DSLAM and associated PVD shelf can provide a maximum of 384 POTS lines, a fourth DSLAM is installed to provide multi-channel POTS capability to individual subscribers as required to complete the full 1200 pairs. Referring to FIG. 6 , connectivity with CO 100 is provided by OC3c connection 610 to FTE 612 and, via OC3c 614 to a first DSLAM 616 . DSLAM 616 is then connected in tandem with DSLAM 622 via OC3c 620 , DSLAM 628 via OC3c 626 and DSLAM 634 via OC3c 632 . PVD shelves 618 , 624 , and 630 , associated with respective DSLAMs 616 , 622 , and 628 , interface via backplane wiring and are interfaced to protector block 638 to SAI 640 to provide a total of 1152 line pairs. The remaining 48 line pairs are individual DSLAM circuits capable of carrying multiple POTS lines are provided directly by DSLAM s. DSLAM 634 likewise is connected via protector 638 to complete the suite of 1200 line pairs supplied to SAI 640 . A power supply including rectifier/battery 636 provides a non-interruptible power source to the equipment and appropriate loop current and signaling power. FIG. 7 shows a configuration of a CO-based DSLAM with PVDs interconnected to a Network Access Service Hub (N.A.S.H.) office. N.A.S.H. office 750 provides a centralized architecture to support local POTS services from a remote switch to the PSTN. FTE 752 is connected to ADM 754 and to ATM 758 via OC3c 756 . In turn, ATM 758 is connected via a second OC3c connection 760 to a next generation switch 762 and thence to an ATM/IP network 764 . ATM/IP network 764 is in turn connected to a media gateway 768 and, via the gateway, to PSTN 770 . CO 702 is connected via Ocn-c (i.e., OC3c or OC48c) to FTE 752 of N.A.S.H. office 750 . Thus, Ocn-c 738 provides connectivity to ADM 736 and, via FTE 732 to tandemly connected DSLAM 710 , 716 and 722 . Because the configuration assumes compressed voice lines, each of the PVDs can support 16 compressed voice lines as opposed to eight non-compressed voice lines. Accordingly, each PVD shelf 712 and 718 can support approximately 800 POTS lines, which are provided via protector 728 and SAI 726 and 728 to the distribution system. DSLAM 722 provides 48 individual DSL circuits to individual customers with multi-channel requirements. FIG. 8 shows details of connections between each of the DSLAM line cards and the associated copper plant. Thus, OC3c 824 a is connected via OC3c NT 822 a to a DSLAM line card 802 a . Each DSLAM line card 802 a includes an asymmetric digital subscriber line (ADSL) input device 810 and an IAD chip set 814 . An output of ADSL input device 810 is connected to IAD chipset 814 via a connection 812 including four ADSL outputs. In turn, IAD chipset 814 is connected to 50 pairs of a 600-pair, 24-gauge cable 820 connecting the line cards to an associated SAI via any required MDF protectors or other related circuitry. While this invention has been described in connection with what is presently considered to be the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It should further be noted and understood that all publications, patents and patent applications mentioned in this specification are indicative of the level of skill of those skilled in the art to which the invention pertains. All publications, patents and patent applications are herein incorporated by reference to the same extent as if each individual publication patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.