Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1998-06-12
2002-02-05
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S351000, C370S353000, C370S354000, C370S356000
Reexamination Certificate
active
06345047
ABSTRACT:
BACKGROUND TO THE INVENTION
1. Field of the invention
The invention relates to apparatus for simultaneously sending a telephone call over a subscriber telephone line from a PSTN compatible telephone terminal on a subscriber site, and IP packets from a first computer, to apparatus for simultaneously receiving a telephone call to a PSTN compatible telephone terminal on the subscriber site, and IP packets directed to a first computer, both sent over a subscriber telephone line, to methods of using such apparatus, and to software for carrying out such methods.
2. Background Art
The most common way of accessing on-line services using the Internet is via a modem link over a dial-up PSTN connection. However, this may tie up the user
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s telephone line for long periods. Incoming and outgoing voice telephone calls cannot be made or completed. Similarly, when the telephone line is being used for a voice telephone call, the Internet cannot be accessed.
One known solution to this problem is to have a second line installed. However, additional expense is involved and the second line may be accessible from only one room in the house or small office, unless major rewiring work is carried out to make both lines accessible in many rooms.
An alternative solution is called the Internet Phonejack. This is a telephony expansion card which can be plugged into a PC, and enables Internet telephony applications such as Microsoft Netmeeting to interface with conventional telephone terminals. The card emulates an ordinary subscriber telephone line, and thus enables such telephone terminals to be used for voice calls at the same time as the computer user is accessing the Internet. The analog voice signals are converted into Internet Protocol (IP) packets which can be interleaved with IP packets used by the computer for accessing other services over the Internet simultaneously.
Another known system is called the Phone Doubler, produced by Ericsson.
FIG. 1
illustrates this known arrangement in schematic form. A user
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s PC (Personal Computer)
20
is connected to a subscriber telephone line using a modem
40
. Phone doubler client software
30
runs on the PC. A headset
10
with microphone and earphone is connected to the PC.
Away from the subscriber
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1
)}
s location, the rest of the PSTN/ISDN 50 links other elements of the arrangement. A VOIP (Voice over Internet Protocol) gateway
70
is connected to the PSTN and to an Internet access server
80
. The VOIP gateway and the Internet access server may be co-located and connected by a local area network such as an ethernet link. The Internet access server is linked to the rest of the Internet
90
, and also to the PSTN.
In operation, when an incoming call from a remote telephone
60
is routed by the PSTN to the subscriber with the PC
20
, if the subscriber is already connected to the Internet over his subscriber line, the local central office (not shown) in the PSTN will be arranged to divert the call to the phone doubler VOIP gateway, assuming the subscriber has previously subscribed to this phone doubler service. The VOIP gateway will receive the call and will look up the IP address of the subscriber, based on the telephone number of the subscriber which has been dialed from the remote telephone
60
. The gateway determines if the user already has an IP session with the Internet access server, and if so, communicates with the phone doubler client software
30
to offer the user the option of taking the call.
If the user accepts the call, the gateway converts the incoming voice signals into UDP (User Datagram Protocol) format, which uses IP for transmission. The phone doubler client
30
receives the IP packets, assembles the UDP datagrams, converts them back into the analog voice signals, which are fed to the headset
10
. Voice signals from the subscriber can be transmitted in a corresponding way back to the remote telephone
60
. This achieves a virtual second line for a user, to enable simultaneous voice and on-line access over a single subscriber line.
It is also known to provide systems to enable multiple computers to access the Internet over a single subscriber line simultaneously. The multiple computers may be connected over a local area network (LAN), and an Internet LAN bridge can be used to enable multiple LAN users to share a single dial-up Internet connection at the same time.
Another known system, called HomeRun has been proposed by TUT Systems, and uses existing telephone wiring in the home or office to create an ethernet LAN. It has been proposed to use this to provide Internet access throughout the home or office by linking all the computers to a modem which can maintain a single dial up connection to an ISP (Internet Service Provider), by creating a LAN over the existing telephone wiring. The networking signals and standard telephone service can coexist on the same wires at the same time, using frequency division multiplexing. Ordinary telephones can be used without alteration. PCs can be plugged in to the telephone sockets using interface cards which support a standard RJ11 phone jack, and include an ethernet interface.
It is also known to modify the equipment at each end of the subscriber telephone line to provide a higher bandwidth service over the subscriber line, e.g. 128 kbps for ISDN (Integrated Services Digital Network) or higher for xDSL (High Speed Digital Subscriber Line) type systems. For an ISDN line, two channels are multiplexed over a single physical path. The interfaces at each end may be arranged so that voice calls use one of the two channels, while the other may be used to carry data, to enable online services to be accessed simultaneously. xDSL encompasses a range of different types of digital subscriber line systems including ADSL (Asynchronous Digital Subscriber Line), requiring specialized equipment at both ends of the subscriber line.
In this document, PSTN compatible telephone terminals shall be defined as excluding ISDN or ADSL compatibility. PSTN compatible is intended to encompass compatibility with a basic public telephone service interface. Such terminals use a conventional tip and ring analog interface, for use with one 64 kbit channel in the PSTN network. They may have a wired handset or a cordless handset, or a speaker phone, for example.
The term IP is intended to encompass any version of the Internet Protocol and any other protocols which may be used for carrying Internet traffic with ISO layer three functions.
SUMMARY OF THE INVENTION
It is an object of the invention to provide improved methods and apparatus.
According to a first aspect of the invention there is provided apparatus for use with a subscriber telephone line connecting a subscriber site and a telephone network, for simultaneously sending a telephone call from a PSTN compatible telephone terminal on the subscriber site, and IP packets from a first computer, over the subscriber telephone line, the apparatus comprising:
a converter having a PSTN compatible telephone line interface for coupling to the PSTN compatible telephone terminal, the converter being for converting signals from the PSTN compatible telephone terminal into IP packets representing the telephone call; and
a multiplexer coupled to the converter, and having a computer interface for coupling to the first computer, and a subscriber line interface for coupling to the subscriber telephone line, the multiplexer being arranged for sending simultaneously the IP packets representing the telephone call and those from the computer, along the subscriber telephone line;
the apparatus being arranged to handle telephone calls without conversion to IP packets, between the telephone terminal and the subscriber telephone line when the subscriber telephone line is not used for carrying IP packets.
One of the problems of the prior art, discovered and addressed by this aspect of the invention is the ability to provide, using one subscriber line, e.g. a conventional POTS (Plain Old Telephone Service) line, that all phones in a household remain ope
Chin Wellington
de Wilton Angela C.
Northern Telecom Limited
Pham Brenda H.
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