Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1997-11-24
2001-12-11
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C379S093090
Reexamination Certificate
active
06330235
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of communication systems and, more particularly, to data communications over a telephone network.
2. Background Information
Land based telephone systems have been in existence for many years. Existing telephone networks use twisted pair copper telephone wire to connect telephones and other equipment to a centralized Public Switched Telephone Network (PSTN) switch located at a Central Office (CO) or remote CO providing connectivity to other telephones or equipment. Up until recently, the predominant use of the twisted pair wire connecting telephones to the PSTN switch has been for traditional telephony functions such as for example voice conversation using a Plain Old Telephone Service (POTS) telephone call. With the advent of Internet and the World Wide Web, the twisted pair wires in existing telephone networks have begun carrying increasing amounts of digitized data for extended periods of time.
To illustrate,
FIG. 1
shows a prior art telephone network
101
including a PSTN switch
105
providing connectivity to a plurality of telephones, such as remote telephones
107
and
109
. As can be appreciated to those skilled in the art, PSTN switch
105
may be any one of a plurality of PSTN switches coupled together in a PSTN. Remote telephone
107
is coupled to PSTN switch
105
through twisted pair wire
115
. Remote telephone
109
is coupled to PSTN switch
105
through twisted pair wire
117
. During typical telephony operation, remote telephone
107
can communicate with remote telephone
109
through twisted pair wire
115
, PSTN switch
105
and twisted pair wires
117
or to any other telephone in the PSTN.
As discussed, there is an increasing demand for telephone network
101
to carry digital information over the existing twisted pair wires to allow remote computer systems, such as for example client system
113
, to communicate other systems, such as for example Internet Service Providers (ISPs), which may be represented as host system
103
in FIG.
1
. Client system
113
is coupled to twisted pair wire
117
through remote modem
111
. Host system
103
is typically coupled to PSTN switch
105
through a high speed data interface
119
. Accordingly, data communications are provided between host system
103
and client system
113
through PSTN switch
105
, twisted pair wire
117
and remote modem
111
.
This continuing trend of using existing telephone networks for data communications has created some concern for the operators of the PSTN since virtually all of their switching equipment was initially intended to carry only short duration voice calls. Indeed, many PSTN switches are carrying more communications traffic volume than which they were originally designed.
In view of the foregoing, what is desired is a method and apparatus that permits data communications at high data rates over existing twisted pair wires of existing telephone networks without burdening the PSTN switches. Furthermore, such a method and apparatus should be able to be coupled to existing PSTN twisted pair wires with little or no modification and without interfering with normal telephony functions.
SUMMARY OF THE INVENTION
A method and apparatus permitting data communications at high data rates over an existing telephone network without interfering with normal telephony functions is disclosed. In one embodiment, a telecommunications system is described, which includes a concentrator coupled between a host system and a telephone line of a PSTN switch. The telephone line couples together the PSTN switch and a remote telephone such that the concentrator is coupled to the telephone line between the PSTN switch and the remote telephone. A remote modem is coupled between a client system and the telephone line such that data communications may be established between the host system and the client system over the telephone line through the concentrator. The data communications between the host and client systems bypass the PSTN switch and occur during an on-hook condition on the telephone line. A detection circuit is coupled to the telephone line and detects when there is an on-hook to off-hook transition on the telephone line. If so, data communications between the host and client systems are suspended, thus enabling normal telephony functions to occur during the off-hook condition on the telephone line. Once the telephone line returns to an on-hook condition, the suspended data communications between the host system and the client system are resumed.
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Grundy Kevin P.
Olson Peter D.
Seamons John K.
Chin Wellington
Hughes Electronics Corporation
Pennie & Edmonds LLP
Yao Kwang B.
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