Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1999-06-04
2004-03-16
Vanderpuye, Kenneth (Department: 2661)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S401000
Reexamination Certificate
active
06707810
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to telecommunications systems and data networks, and more particularly, to systems and methods for establishing direct routing of a signal between communications devices and data networks using a digital loop carrier (“DLC”)
BACKGROUND
Telecommunications networks provide for both local calling within defined regions, and long-distance calling throughout the United States and other countries. These networks may be owned and operated by public and private companies, and governments. Some of these telecommunications networks are for the private use of the owning or operating entity. Others are operated by common carriers or by telecommunications service providers for use by the public or for use by a limited group of subscribers.
Various communications devices may be used to communicate over telephone lines of existing telecommunications networks. Some devices are based on analog technology, such as conventional telephones, since they are designed to support the analog waveforms of human speech. Other devices, such as facsimile (“FAX”) machines and personal computers, are based on digital technology because data processed by these devices is encoded and manipulated in binary strings of data. Personal computers may communicate over telephone lines using modems or other similar devices known to those skilled in the art.
Communications devices, such as telephones or modems, are generally connected to a service switching port (“SSP”) of a local telecommunications network through a pair of wires, generally referred to as a “subscriber loop.” A voltage is applied across the loop by the SSP to power the communications device, and to provide a mechanism for monitoring activity of the communications device. For example, when a calling party lifts the handset of a telephone to initiate a call, a switch in the telephone closes, enabling current to flow between the SSP and the telephone through the loop. The SSP detects current flow in the loop, and recognizes this as an “off-hook” condition. The SSP then transmits a dial tone to the communications device, thus allowing the calling party to dial the number of a called party, the intended recipient for the call.
As explained above, existing telecommunications networks allow for long-distance calling between local networks. Long-distance calling refers generally to the routing of calls over greater distances than those served by a local telecommunications network. For example, a calling party served by an SSP of a first telecommunications network may place a long-distance call to a called party served by an SSP of another telecommunications network over long-distance carriers such as fiber-optic networks. This is typically done by dialing a “1” before dialing the digits of numbers used by the called party.
Amplifiers have typically been used with circuitry for long-distance communication to compensate for signal attenuation as a call signal traverses long-distance circuitry. Because amplifiers are generally unidirectional, however, signals transmitted long-distance between telecommunications networks are generally separated into two distinct paths, such that signal transmission through each path is powered by a respective amplifier. One path is used for transmitting of call signals, and the other path is used for receiving call signals. Such signal splitting results in the use of a four-wire circuit, which is commonly referred to as a “trunk.”
Various types of large capacity telecommunications networks have been specifically developed for the transport of data. These data networks typically use frame-relay (“FR”), asynchronous transfer mode (“ATM”), Internet protocol (“IP”) or other packet-based technologies for data transmission. To send a data signal through a packet-based data network, the signal is first broken into individual blocks or “packets” of limited size. These individual blocks of data are then transmitted through the network and reconstructed upon receipt to form the original signal. The capacity of a data network is generally such that signals may be communicated through the network with minimal cost. Thus, if appropriate systems and methods of transmission are used, data networks may provide relatively cheaper alternatives to conventional telephone networks for local, and particularly long-distance, telecommunications.
Data networks are generally not designed to interface with existing telecommunications networks. This is because data networks typically communicate signals in the form of discrete packets or clocks of digital data, as explained above. On the other hand, telecommunications networks transmit telecommunications signals as continuous analog waveforms. Thus, to transmit an analog voice signal through a data network, for instance, the analog signal is desirably converted to digital form and then divided into blocks of appropriate size. These blocks of digital speech data are then communicated through the data network, individually. After the data blocks pass through the network, the blocks are reassembled, preferably in the order in which they were transmitted, to preserve any messages contained in the original analog voice signal. The reassembled digital voice signal is then converted back to an analog voice signal for communication to the called party.
A need has arisen for an efficient merger of a local telecommunications network, such as a publicly-switched telephone network (“PSTN”), with a data network. Most conventional techniques rely solely on the PSTNs and conventional long-distance publicly-switched telephone lines to establish the long-distance communications path. One example of a conventional long-distance communications system involves computers having video and audio capabilities. Each computer is coupled to a modem operating at, for example, V.34 modem speeds of approximately 33 Kbps. One of the computers calls from an originating telephone line served by a SSP of a first local telecommunications network, to another computer connected to a terminating phone line, served by the SSP of a second local telecommunications network. The connection between local telecommunications networks is made over a dedicated PSTN network trunk. Another example of a conventional long-distance telecommunications system includes “FAX” machines similarly served by respective telecommunications networks and communicating with one another through only PSTNs. These connections require costly equipment, including computers and FAX machines, and therefore are not universally used. A need therefore remains to provide efficient merger of a local telecommunications network with a data network.
Some techniques have recently been developed to support telecommunications over data networks such as the Internet. For example, a first private branch exchange (“PBX”) and a second PBX may be placed in communication with the data network. These PBXs may then be connected via an analog trunk to various communications devices. The equipment responds to dialing, presents a ring voltage when a call is received, and passes caller identification data to a called party for an incoming call. In addition, the equipment presents each PBX with call progress tones such as ring back and busy tones when outbound calls are made. However, limitations exist with this technique since this technique is private, that is, generally within a single organization and not available to the public.
One patent relates to establishing a call path between one PSTN and another PSTN over a data network. Specifically, Land et al. describes a “System and Method for Establishing a Call Telecommunications Path,” in U.S. Pat. No. 5,751,706. The system and method described by Land et al. allow for calls to be placed over packet-based telecommunications networks such as the Internet. As suggested by Land et al., however, calls are to be routed from a communications device such as telephone to a packet-based network through the switching equipment of a telecommunications network such as a PSTN. Land et al. does not disclose
Mak Stephen
Neel Thomas H.
Alcatel
Hoersten Craig A.
Mysliwiec Richard A.
Sewell V. Lawrence
Vanderpuye Kenneth
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