Abstract:
A method for utilizing a household&#39;s existing telephone line wiring and existing analog telephone sets to make VoIP calls and PSTN calls is provided. The method allows the installation of a simple VoIP routing device in the existing wiring without restructuring of the existing wiring or a deployment of a totally separate network. The method deploys a number of mapping devices to take advantages of the un-used wires in the existing wiring. The mapping devices are installed between the wall jacks and the phone sets, and between a wall jack and the VoIP routing device. The installation of the mapping devices is easy and requires no special tools and experienced personnel.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to wiring, and more particularly to a method for connecting a routing device in existing wiring. 
   2. The Prior Arts 
   The rapid advancement of Internet technology has spurred various exciting applications. Among them, VoIP (voice over IP) is probably the most popular and promising one. In the early days of VoIP, hobbyist talked to each other over public Internet using their computers and suffered a great deal from the often-terrible voice quality. As the communications bandwidth is continuously expanded, more effective encoding/decoding schemes are adopted, and interoperability issues are resolved, VoIP has become more and more a serious communications mechanism in recent years to most people, in the office and household alike. 
   On the other hand, conventional analog telephones and public switched telephone network (PSTN) have been with us for more than 100 years. Due to its reliability and ubiquity, voice communications conducted over fixed telephone lines still constitute a very large portion of the world&#39;s voice traffic. It is widely believed that PSTN and VoIP would coexist peacefully with each other for many years to come. 
   Then, the problem becomes how to seamlessly integrate PSTN and VoIP, so that people would enjoy the benefit from the two totally different technologies Traditionally, voice networks (such as PSTN) and data networks (such as Internet) are built on two totally separate infrastructures. Even though carriers around the world are investing astronomical amount of money to build the so-called Next Generation Network (NGN), hoping to have a single backbone for carrying both voice and data traffics, for customer premises such as households and offices, there aren&#39;t many successful integrations of voice networks and data networks. 
   For most, if not all, households, there is an existing wiring for connecting a number of analog telephone sets to one or two telephone lines, which in turn connects to the PSTN. On the data side, some of these households have a dedicated link to public Internet via mechanisms such as ADSL and cable modem, and there is a local area network (wired or wireless) for connecting a number of computing devices in the household and sharing the bandwidth to the Internet. Various approaches have been proposed to integrate the existing telephone line wiring and the local area network so that existing telephone sets could be used to make VoIP calls as well. 
   One such approach is to use a device called IP PBX as shown in  FIG. 1(   a ). As shown in  FIG. 1(   a ), the IP PBX  100  is connected to the PSTN  10  via a telephone line  110  and connected to the telephone sets  60  via a wiring  20 . The IP PBX  100  also connects to the local area network  50  so that the IP PBX  100  shares the dedicated link  130  to the public Internet  30  with computing devices  70 . When a user (not shown) would like to make a call, the user picks up one of the telephone sets  60  and could select to make a PSTN call or a VoIP call by typing on the telephone set  60 &#39;s keypad a special prefix. Based on the prefix, the IP PBX  100  then decides where to route the call. IP PBX is not yet very popular due to its high cost and is usually installed in office environments as there is a large of number of telephone sets and a large amount of voice traffic so as to justify the IP PBX&#39;s high cost. As most offices already have conventional PBX (which could make PSTN calls only) installed, therefore instead of re-investing on a new IP PBX, some offices install a VoIP gateway  160  along with the conventional PBX  150  for converting analog PSTN calls into VoIP calls and routing these calls to the Internet  30 , as shown in  FIG. 1(   b ). 
   For households that have only one or two telephone lines to the PSTN, the IP PBX or VoIP gateway is way too expensive. In addition, installing, using, and maintaining the IP PBX or VoIP gateway usually require experienced personnel, which is also not commonly available in a household. Besides, the installation of the IP PBX  100  or PBX  150  needs to break up the connection between the PSTN  10  and the existing wiring  20  and interpose the IP PBX  100  or PBX  150  therebetween, as shown in  FIGS. 1(   a ) and  1 ( b ). The existing wiring  20  is destructed or altered to accommodate the IP PBX  100  or PBX  150 . Another shortcoming is that, even though a user could still make either PSTN calls or VoIP calls via the IP PBX  100  and the PBX  150 , once the PBXs are not functioning for any reason, all voice communications to the outside world is disrupted. In addition, before the malfunctioned PBXs are fixed or replaced, an experienced technician is required to reconnect the PSTN  10  back to the existing wiring  20  so as to restore voice communications through the PSTN  10 . 
   Therefore, there is a need for a simple infrastructure for households so that existing wiring remains intact, existing analog telephone sets could be used to make VoIP calls and PSTN calls as well, and, when the communications device such as the IP PBX is broken down, the voice communications to the PSTN could be restored easily without an experienced technician. 
   SUMMARY OF THE INVENTION 
   An objective of the present invention is to provide a method for utilizing a household&#39;s existing telephone line wiring and existing analog telephone sets to make VoIP calls and PSTN calls. The method allows the installation of a simple VoIP routing device in the existing wiring without restructuring of the existing wiring or a deployment of a totally separate network. 
   Most of the households are pre-wired to have RJ-11 phone jacks in almost every room of the house. This existing wiring is usually buried in the walls and typically uses the so-called 6P4C cables. A typical 6P4C cable contains six copper wires numbered from 1 to 6. It is a standard that pretty much every voice communication device such as a phone set and a PBX use only the wires  3  and  4  in a 6P4C cable for voice communications with each other and with the PSTN. The rest four wires are not used. 
   The method of the present invention takes advantages of the un-used wires in the existing wiring to achieve the foregoing objectives by deploying a number of mapping devices. The mapping devices are installed between the wall jacks and the phone sets, and between a wall jack and the VoIP routing device. The installation of the mapping devices is easy and requires no special tools and experienced personnel. The existing wiring remains intact and the PSTN is still connected to wires  3  and  4  of the existing wiring. 
   Through the mapping devices, the telephone sets are connected actually to wires  2  and  5  of the existing wiring, instead of the standard wires  3  and  4 , and, the telephone sets are, thereby, detached from the PSTN. On the other hand, the VoIP device is also connected to wires  2  and  5  of the existing wiring through a mapping device, so as to receive calls from the telephone sets via wires  2  and  5  of the existing wiring. The VoIP routing device is also connected to wires  3  and  4  of the existing wiring which, in turn, is connected to the PSTN. The VoIP routing device is also connected to the Internet for making VoIP calls. 
   The present invention functions as follows. When an inbound call comes in from the PSTN via wires  3  and  4  of the existing wiring, the VoIP routing device detects the call and bridges it to wires  2  and  5  of the existing wiring. All the phone sets, as now connected to wires  2  and  5  of the existing wiring, would ring and could be picked up to answer the inbound call. To make an outbound call, a user picks up one of the phone sets, the VoIP routing device detects the off-hook through wires  2  and  5  of the existing wiring, provides a dial tone, and waits for the user to dial. If the user&#39;s dial digits do not have a special prefix, the VoIP routing device routs the call to the PSTN via wires  3  and  4  of the existing wiring. If the user&#39;s dial digits do have a special prefix, the VoIP routing device routs the call to the Internet by converting it into a VoIP call. Depending on the VoIP routing device, it is also possible that the default route is to the Internet, while a special dialing prefix directs the call to the PSTN. If the VoIP routing device does not function for any reason, a user could simply remove the mapping devices and reconnect the phone sets to the wall jacks, and the connection to the PSTN would be restored instantly without using special tools or waiting for some technician to show up. 
   The foregoing and other objects, features, aspects and advantages of the present invention will become better understood from a careful reading of a detailed description provided herein below with appropriate reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1(   a ) and  1 ( b ) are schematic diagrams for showing the applications of an IP PBX and a VoIP gateway respectively. 
       FIG. 2  is a schematic diagram showing the typical wiring in a household. 
       FIG. 3  is a schematic conceptual diagram showing the typical wiring in a household. 
       FIG. 4  is a schematic diagram showing the connection of a routing device in an existing wiring. 
       FIGS. 5(   a ) and  5 ( b ) are schematic diagrams showing the connection of a routing device in an existing wiring according to the present invention. 
       FIGS. 6(   a )- 6 ( d ) are schematic diagrams showing various embodiments of the mapping device according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following, detailed description along with the accompanied drawings is given to better explain preferred embodiments of the present invention. Please be noted that, in the accompanied drawings, some parts are not drawn to scale or are somewhat exaggerated, so that people skilled in the art can better understand the principles of the present invention. 
   The present invention provides a method for integrating a VoIP routing device into an existing wiring of a household, a small office/home office, or other similar environment. The existing wiring is laid out between a first communication network and at least a client device. The existing wiring contains a number of cables, each of which contains at least four electrically conductive wires. The first communication network and the client device communicate with each other using only two wires of the existing wiring. The first communication network is the PSTN or any similar network using two wires for voice communications. The client device could be a wired phone set, a fax machine, an answering machine, a cordless phone, a modem, or a computer with a built-in modem.  FIG. 2  is a schematic diagram showing the typical wiring in a household. As shown in  FIG. 2 , the existing wiring  20  in a household contains a cable  210  between the PSTN  10  and a punch-down block  220 . The existing wiring further contains a cable  230  between the punch-down block  220  and a wall jack  240 , and a cable  250  between the punch-down block  220  and another wall jack  260 . The four wires of the cables  210 ,  230 , and  250  are connected to each other at the punch-down block  220 . Then from the wall jacks  240  and  260 , two client devices  60  are connected via another two cables  270  and  280 . The cables  270  and  280  could contain four wires or two wires, since the client devices and the first communication network only communicate with each other using two wires. 
   For simplicity sake, the existing wiring  20  could be considered conceptually as a bus containing four wires, instead of containing a punch-down block, a number of cables, and a number of wall jacks, as shown in  FIG. 3 . The four wires are numbered as  2 ,  3 ,  4 , and  5  respectively. The two wires used by the client device and the PSTN are wires  3  and  4 . The wires  2  and  5  are not used. Please be noted that, for simplicity sake, the wires are numbered here in accordance to the current wiring practice. This is not intended to limit the present invention in any specific way. The major principle behind the present invention is to utilize two un-used wires in the existing wiring to achieve the foregoing objectives. How the two wires are numbered is of no significance here. 
     FIG. 4  is a schematic diagram showing a VoIP routing device connected to a household&#39;s existing wiring. As shown in  FIG. 4 , a typical VoIP routing device  400  contains, amongst other things, at least a foreign exchange subscriber (FXS) port  410  for connecting to a client device  80 , at least a foreign exchange office (FXO) port  420  for connecting to the PSTN  10 , and at least a LAN port  430  for connecting to a second communication network. The second communication network here is the Internet  30  behind a local area network  50 . As can be seen, there are a lot of details omitted in  FIG. 4  such as an ADSL modem, a router, and a LAN switch, etc. These details are not relevant to the description of the present invention and therefore are omitted. The VoIP routing device  400  could be a simple IP PBX or similar device that allows a user to make calls either to the PSTN (the first communication network) or to the Internet (the second communication network). Please be noted that the present invention could be applied to various routing devices other than those providing VoIP function. The major characteristic of the routing devices is that it provides at least two separate routes for voice calls to two separate networks respectively. For example, there are routing devices connecting to phone lines from multiple carriers and providing the so-called least cost routing. The least cost routing device automatically selects a carrier&#39;s PSTN network that is least expensive to route a call based on the call&#39;s destination number. In the following, a VoIP routing device is used as an example and is referred to as routing device hereinafter. 
   The FXS port  410  provides loop current, dial tone, and ring voltage, etc. to a connected client device  80 . When a user (not shown) picks up the client device  80 , the routing device  400  provides a dial tone to the client device  80  and accepts the user&#39;s dialing sequence. Based on the dialing sequence, the routing device  400  is able to decide where to route the call. For example, when the user dials “*#*” and the destination number, the “*#*” prefix signals the routing device  400  to make a VoIP call through its LAN port  430 . If the user dials the destination number directly without any prefix, the routing device  400  routes the call to the PSTN  10 . Both the FXS and FXO ports  410  and  420  use only two wires in the connecting cables to communicate with the client device  80  and the PSTN  10  respectively. 
   As can be seen from  FIG. 4 , a separate client device  80  is arranged in order to make and receive calls through the routing device  400 , while leaving the existing client devices  60  for calls to and from the PSTN only. The present invention provides a non-intrusive method for connecting a routing device so that existing client devices  60  could also enjoy the benefit of the routing device while keeping the existing wiring intact.  FIG. 5(   a ) is a schematic diagram for connecting a routing device in an existing wiring according to a preferred embodiment of the present invention. As shown in  FIG. 5(   a ), a number of mapping devices  510  and  520  are installed between the existing wiring  20  and the client devices  60 , and between the existing wiring  20  and the routing device  400 . The mapping devices  510  and  520  are arranged so that the client devices  60  are actually connected to the originally un-used wires  2  and  5  of the existing wiring, which in turn are connected to the routing device  400 &#39;s FXS port  410 . On the other hand, the PSTN  10  is, as usual, connected to the routing device  400 &#39;s FXO port  420  via the wires  3  and  4  of the existing wiring. In  FIG. 5(   a ), the local area network  50  and the Internet  30  are entirely separated from the existing wiring  20 . This scenario is true when the Internet connectivity is established via mechanisms such as cable modem, satellite link, or GSM/GPRS wireless interface. The local area network  50  also seems to be a wired network.  FIG. 5(   b ) is another schematic diagram showing an application scenario of a preferred embodiment of the present invention, involving ADSL for Internet connectivity and wireless local area network. Using  FIG. 5(   b ) as an example, please be noted that the present invention could actually be applied to various types of environments involving different types of Internet connectivity and local area network.  FIGS. 5(   a ) and  5 ( b ) should only be considered examples and are not intended to limit the present invention in any way. As shown in  FIG. 5(   b ), the phone line extended from the carrier&#39;s central office  32  is connected to the wires  3  and  4  of the existing wiring  20 . A mapping device  520 , which will be explained in details later, takes the four wires of the existing wiring  20  and separate them into two pairs. One pair consisting of the wires  2  and  5  is connected to the FXS port  410  of the routing device  400 . The other pair consisting of the wires  3  and  4  passes through the splitter  52  and breaks out another two pairs of wires. One of them is connected to the FXO port  420  of the routing device  400  for making calls to the PSTN  10 . The other one is connected to the ADSL modem  54  for establishing connectivity to the Internet  30 . The ADSL modem  54  is connected to the LAN switch  56  using a RJ-45 cable (not numbered). The LAN switch  56  and the wireless access point  58  make up the local area network  50 . The LAN port  430  of the routing device  400  is also connected to the LAN switch  56  via a RJ-45 cable, as well as the wireless access point  58 . The wireless access point  58  provides a wireless coverage with which the client device  70  is covered. As can be seen from  FIG. 5(   b ), a simple installation of the mapping device  520  seamlessly integrates the routing device  400  with the existing wiring. 
     FIGS. 6(   a )- 6 ( c ) show preferred embodiments of the mapping device  510  for connecting the client device  60  with a wall jack  610 . The wall jack  610  has four pins numbered from 2 to 5 and the four pins are connected to the corresponding four wires 2 to 5 of the existing wiring  20  respectively. As shown in  FIG. 6(   a ), the mapping device  510  is a cable containing four wires (not numbered) only and two RJ-11 connectors (not shown) at its two ends. The four wires are arranged so that, when the mapping device  510  is installed between the wall jack  610  and the client device  60 &#39;s set jack  62 , the wall jacks  610 &#39;s pins  2 ,  5  (and, therefore, wires  2 ,  5  of the existing wiring) are connected to the set jack  62 &#39;s pins  3 ,  4 , and the wall jacks  610 &#39;s pins  3 ,  4  (and, therefore, wires  3 ,  4  of the existing wiring) are connected to the set jack  62 &#39;s pins  2 ,  5 . In another embodiment, the mapping device  510  contains only two wires that connect the wall jacks  610 &#39;s pins  2 ,  5  to the set jack  62 &#39;s pins  3 ,  4 , respectively. The previous embodiment is more convenient as a user could plug either end of the mapping device  510  to either a wall jack  610  or a set jack  62 . To set up the client device  60  for dialing both PSTN and VoIP calls, a user simply replaces the original cable between the wall jack  610  and the set jack  62  with the mapping device  510  depicted in  FIG. 6(   a ). 
   Similarly, as shown in  FIG. 6(   b ), the mapping device  510  could be implemented as a cable containing two wires, a RJ-11 connector (not shown) at one end for plugging into the wall jack  610 , and a RJ-11 socket  512  at the other end for receiving an cable  64 &#39;s RJ-11 connector (not shown). The wire arrangement is such that the wall jack  610 &#39;s pins  2 ,  5  are connected to the socket  512 &#39;s pins  3 ,  4 . In a similar embodiment, the mapping device  510  contains four wires arranged identical to that depicted in  FIG. 6(   a ). To set up the client device  60  that originally connects to the wall jack  610  via the cable  64  for dialing both PSTN and VoIP calls, a user simply un-plugs the cable  64  from the wall jack  610 , and uses the mapping device  510  depicted in  FIG. 6(   b ) to connect the wall jack  610  and the cable  64 .  FIG. 6(   c ) shows another embodiment of the mapping device  510 . In this embodiment, the mapping device  510  is a coupler with two RJ-11 sockets  514  and  516 , interposed between two four-wire cables  66  and  68 . Inside the coupler, the two RJ-11 sockets are arranged so that pins  2 ,  5  of one socket are connected to pins  3 ,  4  of the other socket. 
     FIG. 6(   d ) shows an embodiment of the mapping device  520  for connecting the wall jack  610  and the routing device  400 . The mapping device could actually be used to connect client device  60  as well, as will be explained later. As shown in  FIG. 6(   d ), the mapping device  520  is a cable containing four wires, a RJ-11 connector (not shown) on one end for plugging into the wall jack  610 , and two RJ-11 sockets  522  and  524  on the other end. The four wires inside the mapping device  520  are arranged so that the wall jack&#39;s pins  2 ,  5  are connected to the socket  524 &#39;s pins  3 ,  4 , while the wall jack&#39;s pins  3 ,  4  are connected to the socket  522 &#39;s pins  3  and  4 . The two sockets  522  and  524  then connect to the routing device  400 &#39;s FXO port  420  and FXS port  410  via two straight cables  440  and  450  respectively. The mapping device  520  could be used to connect client device  60  as well, by installing a straight cable between the socket  524  and the set jack  62 . 
   Although the present invention has been described with reference to the preferred embodiments, it will be understood that the invention is not limited to the details described thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.