Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1998-03-31
2004-03-23
Kizou, Hassan (Department: 2662)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S401000, C379S088170, C379S093070, C379S900000
Reexamination Certificate
active
06711160
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to communication systems, and more particularly, to a device for communicating voice data over a packet-based data network.
BACKGROUND ART
Currently, programs are available for digitizing the voice data as a person talks, and sending the digital data over the Internet. The existing programs are designed to run on a personal computer having a sound card with speakers and microphones. Accordingly, the only way to utilize the existing programs is to power on the personal computer before getting a voice connection through the Internet. In addition, the programs are capable of being used only in conjunction with a browser, for example, when navigating on the World Wide Web (Web) over the Internet. Moreover, the existing programs allow calling only those on the Internet having a compatible phone software, that is, a same type of compression scheme. They also do not automatically provide a capability for calling a party on the public switched telephone network, unless another connection is made to a “phone gateway”.
The U.S. Pat. No. 5,526,353 by Henley et al. is a system and method for communicating audio data in a packet-based computer network where transmission of data packets through the computer network requires variable periods of transmission time. The system described in this patent requires a PC connection for delivering voice data over the packet network. It also does not include any other additional functions the present invention is able to provide.
SUMMARY OF THE INVENTION
The present invention is a standalone packet network phone interface unit which enables a plain old telephone instrument or a fax machine to be connected directly to a packet network. The present invention may be used without having a personal computer (PC), and provides, inter alia, features such as a plain old telephone set (POTS) interface to a packet network, a “phone gateway” capability, and an “IP phone” capability. Yet another feature of the present invention is an ability to connect to various serial communications mediums such as the cable TV channels and the integrated services digital network (ISDN). Such connections are useful for making telephone calls that bypass a local loop and/or local telephone company. Other features provided by the present invention include an ability to identify a caller id and display the information; a switch option to connect directly to a public switched telephone network (PSTN) line; and, an interface to connect to a data terminal equipment such as a PC.
The apparatus of the invention includes an analog to digital/digital to analog converter for converting voice signals to digital signals and vice versa; a signal processor for filtering and encoding the converted digital signals whose functions may also include operating as a modem; a network interface card for providing a physical connection to a network for transmitting and receiving packets of data from a network; a system controller for controlling and manipulating data, signals and their flow; and various additional interfacing devices for connecting to the external mediums, including a two-wire to four-wire converter for electrically connecting the telephone instrument. The system of this invention may further include an erasable and electrically programmable read only memory, said memory having capacity to be programmed remotely and dynamically.
The apparatus of the present invention is connected to a packet network and receives and transmits real time data such as voice samples from and to the network. The apparatus includes a network interface card and a controller for receiving packets from the network having an IP address corresponding to the network address of the apparatus. The controller strips off headers and trailers from each data packet received. The stripped data packets are generated into a stream of digital data which then is converted to analog audio data and transmitted to a telephone instrument. Similarly, audio data received from the telephone instrument is converted and compressed into digital data, assembled into packets with headers and trailers, and transmitted to the network via the network interface card. Accordingly, it is the object of this invention to provide a standalone interface between the POTS and the packet-based data network such that the apparatus of the present invention may be used as a terminal equipment of a packet data network phone system.
The present invention also functions as a one line PSTN gateway to the packet network by utilizing the data access arrangement (DAA). The DAA is directly connected to an analog line and interfaces with the PSTN. The DAA module performs, inter alia, over voltage protection, two-wire to four-wire signal conversion, ring detection, and off-hook on-hook detection and generation.
When the present system is functioning as a “phone gateway”, a signal processor incorporated in the present invention performs dial tone detection and generation, dual tone multi-frequency (DTMF) tone generation and detection, voice compression and decompression, transmissions of off-hook signals to the DAA, and echo cancellation and suppression.
The system controller, also incorporated in the present invention, plays a pre-recorded message to announce to a caller on the PSTN side to press the destination number. The system controller then transfers the number to the telephony server on the digital data network to map it to an appropriate network address such as an IP address. The telephony server returns the network address to the system controller in the present invention to be used for further communication. If the call is initiated from the digital data network side, the system controller takes the destination number and passes it to the signal controller which then generates DTMF tones to make a call out to the PSTN. Accordingly, it is yet another object of this invention to provide a public switched telephone network gateway to a digital network phone system.
The apparatus of the present invention also provides means for connecting a data terminal equipment such as a PC. With a PC connection to the system of the present invention, many different feats may be accomplished. For example, a user may download via the PC a program for simultaneous voice data (SVD) function. The SVD function program enables the user with a single telephone line to speak on a telephone via Internet telephony while at the same time navigating among Web pages. In this way, the PC need not be equipped with a sound card, a microphone, or a speaker when making a phone call to the IP network. Yet, by downloading the SVD function program, the present system may effectively function as an “IP phone”.
Other uses for connecting to a data terminal include information exchange for speed dial, automatic dialer, call detail records, dynamic firmware upgrade, caller identification record, voice mail, and normal everyday computer interface. Accordingly, it is a further object of this invention to provide an interface for connecting the present invention with a data terminal equipment such as a PC.
The present invention also includes a fallback switch for connecting a telephone instrument directly to the PSTN. This switch provides an option for connecting either to the PSTN line or a packet network. When the system of the present invention detects a power-off state, it automatically provides a direct connection from the telephone set to the PSTN line. That is, when a power is turned off on the apparatus of the present invention or if a power failure occurs, a phone call will be made directly through a telephone line, not any different from the way a plain everyday telephone call is made.
In addition, the system provides an option for the user to connect directly through the PSTN line instead of communicating through the packet network. That is, the user may choose to use a telephone set connected to the system to make a call via a conventional telephone line and the PSTN. The system includes a logic for determining whether a call will be made
Chan Shun-Shing
Lee Nathan Junsup
Maruyama Kiyoshi
Cameron Douglas W.
Elallam Ahmad
International Business Machines - Corporation
Kizou Hassan
Scully Scott Murphy & Presser
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