The present invention relates to the field of telephony systems within a house, used for home, office, enterprise or factory applications, connected to a network.
Telephony, Definitions and Background
The term “telephony” herein denotes in general any kind of telephone service, including analog and digital service, such as Integrated Services Digital Network (ISDN).
Analog telephony, popularly known as “Plain Old Telephone Service” (“POTS”) has been in existence for over 100 years, and is well designed and well-engineered for the transmission and switching of voice signals in the 3-4 KHz portion (or “voice-band”) of the audio spectrum. The familiar POTS network supports real-time, low-latency, high-reliability, moderate-fidelity voice telephony, and is capable of establishing a session between two end-points, each using an analog telephone set.
The terms “telephone”, “telephone set”, and “telephone device” herein denote any apparatus, without limitation, which can connect to a Telco operated Public Switched Telephone Network (“PSTN”), including apparatus for both analog and digital telephony, non-limiting examples of which are analog telephones, digital telephones, facsimile (“fax”) machines, automatic telephone answering machines, voice modems, and data modems.
The term “network” herein denotes any system that allows multiple devices to send and receive information of any kind, wherein each device may be uniquely identified for purposes of sending and receiving information. Networks include, but are not limited to, data networks, control networks, cable networks, and telephone networks. A network according to the present invention can be a local area network (LAN) or part of a wide-area network, including the Internet.
Telephone System
FIG. 1 shows a typical telephone system installation in a house. The Figure shows a network 10 for a residence or other building, wired with a telephone line 14, which has a single wire pair that connects to a junction-box (not shown), which in turn connects to a Public Switched Telephone Network (PSTN) 11 via a cable (‘local loop’) 15a, terminating in a public switch, which establishes and enables telephony from one telephone to another. A plurality of telephones 13a and 13b may connect to telephone lines 14 via a plurality of telephone outlets 12a and 12b. Each outlet has a connector (often referred to as a “jack”), commonly being in the form of RJ-11 connectors in North-America. Each outlet may be connected to a telephone unit via a compatible “plug” connector that inserts into the jack.
Wiring 14 is normally based on a serial or “daisy-chained” topology, wherein the wiring is connected from one outlet to the next in a linear manner; but other topologies such as star, tree, or any arbitrary topology may also be used. Regardless of the topology, however, the telephone wiring system within a residence always uses wired medium: two or four copper wires terminating in one or more outlets which provide direct access to these wires for connecting to telephone sets.
Outlets
The term “outlet” herein denotes an electro-mechanical device that facilitates easy, rapid connection and disconnection of external devices to and from wiring installed within a building. An outlet commonly has a fixed connection to the wiring, and permits the easy connection of external devices as desired, commonly by means of an integrated connector in a faceplate. The outlet is normally mechanically attached to, or mounted in, a wall. Non-limiting examples of common outlets include: telephone outlets for connecting telephones and related devices; outlets used as part of ‘structured wiring’ infrastructure (e.g. for Ethernet based network), telephone outlets for connecting telephone sets to the PSTN, CATV outlets for connecting television sets, VCR's, and the like; and electrical outlets for connecting power to electrical appliances. An outlet as used herein, can also be a device composed of a part that has a fixed connection to the wiring and is mechanically attached to, or mounted in, a wall, and a part that is removably mechanically attached and electrically connected to the first-mentioned part, i.e. a device in which the first part is a jack or connector used for both electrical connection and mechanical attachment. The term “wall” herein denotes any interior or exterior surface of a building, including, but not limited to, ceilings and floors, in addition to vertical walls. Telephone installation in recently built residential houses and common in offices is shown in FIG. 2, allowing for external multi-telephone lines connection and for various switching functionalities (e.g. intercom). The installation 20 is based on ‘star’ topology and employing PBX 12, having multiple telephone ports. Telephones 17a, 17b, 17c and 17d are each distinctly connected to a different PBX 12 ports via connections 21a, 21b, 21c and 21d respectively. The PBX 12 also provides three ports for incoming telephone lines 15a, 15b and 15c originated in the PSTN 11.
POTS Multiplexer
Typically each POTS telephone connection requires an independent wire pair. In the case wherein multiple telephone lines are carried between two points, many wire pairs are thus required. In order to allow for carrying multiple telephone services over several copper pairs, a POTS multiplexer system is commonly used (also known as DLC—digital Loop Carrier). Basically, the telephony signals are carried in digitized and multiplexed form over a cable comprising one or two wire pairs. Such a system is shown in FIG. 3, describing POTS multiplexer system 30 based on exchange side mux/demux 33 and customer side mux/demux 34, connected by two wires 32a and 32b. Telephone lines 31a, 31b, 31c and 31d from the PSTN 11 are connected to the exchange side mux/demux 33, wherein the incoming signals are digitized and multiplexed (commonly time multiplexed TDM, such as E1 or T1 systems), and transmitted over the wire pair 32 to the customer side mux/demux 34. The digitized telephony signals are demultiplexed and restored as analog POTS form, and fed to the respective telephone sets 17a, 17b, 17c and 17d via links 35a, 35b, 35c and 35d respectively, connected to the appropriate customer side mux/demux 34. The process is simultaneously applied in the telephone sets to PSTN direction, hence supporting full telephone service. WO 97/19533 to Depue teaches an example of such POTS multiplexer. Commonly, such prior art systems do not provide any switching functionality, and are mainly used for carrying multiple telephone signals from one point to another remote point. As such, cabling 35 is required from each telephone set 17 to the relevant port of customer side unit 34. Similarly, WO 01/28215 to Bullock et al. teaches a POTS multiplexer over power-lines.
WO 01/80595 to the same inventor of this application teaches a system allowing for reduced cabling requirements. The system 40 shown in FIG. 4 is based on ‘distributed’ customer side mux/demux 34. A PBX/MUX 12 connects to the PSTN 11 for multiple incoming telephone lines 15a, 15b and 15c, similar to the function of the exchange side mux/demux 33 of system 30. However, as a substitute to the single customer side mux/demux 34 multiple mux units 41 are provided. Telephone sets 17a, 17b and 17c are respectively coupled to mux units 41a, 41b and 41c. The mux units 41a, 41b, 41c and PBX/MUX 12 digitally communicate with each other, allowing each telephone set to connect to any of the incoming lines 15 or to another telephone set for intercom function. In such a way, there is no need to route new cable from each telephone set to a central place, but rather to a nearby mux unit 41.
Voice over Internet Protocol (VoIP)
Recently, a solution for combining both telephony and data communications into a single network is offered by the Voice-over-Internet-Protocol (VoIP) approach. In this technique, telephone signals are digitized and carried as data across the LAN. Such systems are known in the art, and an example of such a system 50 is shown in FIG. 5. The system 50 is based on a Local Area Network (LAN) 53 environment, commonly using Ethernet IEEE802.3 standard interfaces and structure. The LAN can be used to interconnect computers (not shown) as well as other end-units, as well as IP telephone sets 54a, 54b and 54c shown. An example of IP telephone set 54 is Voice Service IP-Phone model DPH-100M/H from D-Link Systems, Inc. of Irvine, Calif., USA. IP-PBX unit 52 is also connected to the LAN and manages the voice data routing in the system. Many routing protocols are available, such as IETF RFC 3261SIP (Session Initiation Protocol), ITU-T H.323 and IETF RFC 2705 MGCP (Media Gateway Control Protocol). Examples of such a SIP based IP-PBX 52 is ICP (integrated Communication Platform) Model 3050 from Mitel Networks of Ottawa, Ontario Canada. Connection to the PSTN 11 is made via VoIP Gateway 55a, operative to convert an incoming analog POTS telephone signal to a digital and IP packet based protocol used over the LAN. An example of such VoIP Gateway 55 supporting four PSTN lines is MediaPack™ Series MP-104/FXO of AudioCodes Ltd. In Yehud, Israel. Such a system 50 allows for full telephone connectivity similar to performance of POTS PBX-based system (such as in FIG. 2). In most cases, such a network allows also for data networking (non-voice traffic), such as computers and peripherals, and connection to the Internet.
A VoIP MTA (Multimedia Terminal Adapter) is also known in the art, operative to convert IP protocol carrying telephony signals into POTS telephone set interface. Examples of such a VoIP MTA supporting four POTS telephone sets are MediaPack™ Series MP-104/FXS of AudioCodes Ltd. In Yehud, Israel and two-ports Voice Service Gateway model DVG-1120 from D-Link® Systems, Inc. of Irvine, Calif., USA. A system 60 shown in FIG. 6 demonstrates the use of such VoIP MTAs 64. The system 60 is identical to system 50, except for replacing the IP phones 54b and 54c with POTS telephone sets 17a and 17b. In order to enable the usage of these telephone sets 17a and 17b, respective VoIP MTAs 64a and 64b are added as the mediation devices between the analog telephony and the IP telephony. The addition of MTAs 64 allows for the same basic system functionality, although POTS telephones 17 are used rather than IP telephones 54. The combination of telephone set 17 connected to VoIP MTA 64 allows connection to an IP network, in the same manner that the IP telephone 54 is connected thereto, and providing similar functionality. EP 0824298 to Harper teaches an example a network conforming to such a system.
An example of the system 60 based on IP/Ethernet (IEEE802.3) LAN as internal network 53 is shown in FIG. 7 as system 70. The LAN comprises a switch 71 as a multi-port concentrating device in a ‘star’ topology wiring structure. It is understood that any type of device having multiple network interfaces and supporting a suitable connectivity can be used, non-limiting examples of which include a shared hub, switch (switched hub), router, and gateway. Hence, the term “switch” used herein denotes any such device. An example of the switch 71 is DSS-8+ Dual-Speed 8-Port Desktop Switch from D-Link Systems, Inc. of Irvine, Calif., USA, having 8 ports. The network 70 comprises a dedicated cabling 73, such as Category 5 ‘Structured Wiring’. Such a network commonly uses 10BaseT or 100BaseTX Ethernet IEEE802.3 interfaces and topology. In such a network, outlets 72a, 72b and 72c are connected to the switch 71 via respective cables 73a, 73b and 73c. POTS Telephone sets 17a and 17b are connected via respective VoIP MTAs 64a and 64b to the respective outlets 72a and 72b, using connections 74a and 74b respectively. IP Telephone 54a connects directly (without VoIP MTA) via a connection 74c to the outlet 72c, which connects to a port in the switch 71 via cable 73c. The internal network connects to PSTN 11 via VoIP gateway 55a connected to another port of the switch 71, and IP-PBX 52 connects to another port of switch 71. Such a network allows for the telephones 17a, 17b and 54a to interconnect and also to connect to the external PSTN 11.
Home Networks
Implementing a network 70 in existing buildings typically requires installation of new wiring infrastructure 73. Such installation of new wiring may be impractical, expensive and hassle-oriented. As a result, many technologies (referred to as “no new wires” technologies) have been proposed in order to facilitate a LAN in a building without adding new wiring. Some of these techniques use existing wiring used also for other purposes such as telephone, electricity, cable television, and so forth. Doing so offers the advantage of being able to install such systems and networks without the additional and often substantial cost of installing separate wiring within the building. In order to facilitate multiple use of wiring within a building, specialized outlets are sometimes installed, which allow access to the wiring for multiple purposes. An example of home networking over coaxial cables using outlets is described in WO 02/065229 published 22 Aug., 2002 entitled: ‘Cableran Networking over Coaxial Cables’ to Cohen et al.
Other ‘no new wire’ technologies employ non-wired media. Some use Infrared as the communication medium, while others use radio frequency communication, such as IEEE802.11 and BlueTooth.
An example of a network 60 in a house based on using powerline-based home network implementing network 53 is shown as network 80 in FIG. 8. The medium for networking is the in-house power lines 81, which are used for carrying both the mains power and the data communication signals. For the sake of simplicity, the power related functions are not shown in the Figure. A PLC modem 82 converts data communication interface (such as Ethernet IEEE802.3) to a signal which can be carried over the power lines, without affecting and being affected by the power signal available over those wires. An example of such PLC modem 82 is HomePlug1.0 based Ethernet-to-Powerline Bridge model DHP-100 from D-Link Systems, Inc. of Irvine, Calif., USA. D-Link is a registered trademark of D-Link Systems, Inc. PLCs 82a, 82b, 82c, 82d and 82e are all connected to the powerline 81 via the respective power outlets 88a, 88b, 88c, 88d and 88e, forming a local area network over the powerline allowing for data networking for the units connected thereto. The connection is commonly effected by a cord connected to a power outlet being part of the power line medium 81. Such a network 80 allows for the IP-PBX 52, PSTN 11 via VoIP gateway 55a, telephones 17a and 17b via the respective VoIP MTAs 64a and 64b and IP telephone 54a to communicate with each other, as well as to share external connection to the PSTN 11, as was offered by network 70. However, no additional and dedicated wiring is required.
Another home network medium may be the telephone wiring. It is often desirable to use existing telephone wiring simultaneously for both telephony and data networking. In this way, establishing a new local area network in a home or other building is simplified, because there is no need to install additional wiring.
The PLC modem 82 uses the well-known technique of frequency domain/division multiplexing (FDM), and provides means for splitting the bandwidth carried by a wire into a low-frequency band capable of carrying an analog telephony signal and a high-frequency band capable of carrying data communication or other signals. Examples of relevant prior-art in this field are the technology commonly known as HomePNA (Home Phoneline Networking Alliance), WO 99/12330 to Foley and as disclosed in U.S. Pat. No. 5,896,443 to Dichter (hereinafter referred to as “Dichter”). Dichter and others suggest a method and apparatus for applying a frequency domain/division multiplexing (FDM) technique for residential telephone wiring, enabling the simultaneous carrying of telephony and data communication signals. The available bandwidth over the wiring is split into a low-frequency band capable of carrying an analog telephony signal and the ADSL signals, and a high-frequency band capable of carrying home network communication signals. In such a mechanism, telephony and ADSL are not affected, while a home networking communication capability is provided over existing telephone wiring within a house. WO 01/71980 published Sep. 27, 2001 entitled “Telephone Outlet and System for a Local Area Network Over Telephone Lines” and WO 03/005691 published Jan. 16, 2003 entitled “Telephone outlet with packet telephony adapter, and a network using same” both in the name the present inventor and assigned to the present assignee, and which are incorporated by reference for all purposes as if fully set forth herein, describe home networking over telephone wiring, based on outlets, which allows for conducting of digital telephony data as well as POTS and ADSL signals over in-house telephony wiring. Similarly, U.S. Pat. No. 6,130,893 to Whittaker et al. teaches an IP-based telephony network based on telephone wiring.
Many of the above figures and networks involve external connection to the PSTN to provide telephony services over telephone-dedicated wiring and owned by a telephone company. However, there are today multiple technologies for connecting premises to external telephone services, both terrestrial and via the air:    1. Cable television cabling, mostly coaxial cable based, used for delivering video channels, as well as broadband data and telephony to the house.    2. Satellite communication.    3. Power lines communication, wherein the power lines carrying power to the house are also used for data communication.    4. Wireless communications using radio frequency such as cellular, LMDS and many other wireless technologies.    5. Fiber, such as Fiber-To-The-Home (FTTH) or other similar technologies.
The availability of plural telephone service providers, each using a different access medium, allows for a house dweller, for example, to have multiple telephone lines from different providers. For example, a telephone line may be available from the CATV provider, added to the traditional telco oriented telephone line.
Common to all above prior art systems, the incoming telephone lines into the house are connected to a single unit: PBX 12 of system 20 in FIG. 2, exchange side mux/demux 33 of system 30 in FIG. 3, PBX/MUX 12 of system 40 in FIG. 4 and VoIP gateway 55a of systems 50 and 60 in FIGS. 5 and 6, respectively. However, the additional telephone line, for example from the CATV provider, may be available in a distinctly different place. An example of system 20 modified to support both telco (PSTN) and CATV originated telephone lines is shown as system 90 in FIG. 9. In addition to connections to the PSTN 11, an incoming telephone line from CATV network 91 via VoIP gateway 55b is shown. Typically the VoIP gateway is integrated into a cable-modem or set-top-box, and connects to the CATV network 91 via a CATV outlet, connecting to the coaxial cable wiring installation. Since in most cases the VoIP gateway 55b is not located near the PBX 12, there is a need to install new cable 92 from the VoIP gateway 55b to a port in the PBX 12. Such installation is expensive, time consuming and not aesthetic.
There is thus a widely recognized need for, and it would be highly advantageous to have, a method and system for allowing easy and minimum cabling structure for sharing the telephony service from multiple sources or being fed at distinct locations. This goal is met by the present invention.