Serial telephone adapter

• US 6,175,565 B1
• Filed: 09/17/1997
• Issued: 01/16/2001
• Est. Priority Date: 09/17/1997
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Nokia Corporation
• Inventors: Pek, Jiri, McKinnon, Peter
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): Pezzlo, John
• Application Number:
  US08/932,305
• Time in Patent Office: 1,217 Days
• Field of Search: 370/352, 370/401, 370/356, 370/468, 370/349, 370/217, 370/354, 370/242, 375/222, 379/900, 379/212, 379/93.01, 703/23, 395/500, 709/202, 709/203
• US Class Current: 370/354
• CPC Class Codes: H04L 12/5692 Selection among different networks
• CPC Class Codes: H04M 1/2535 adapted for voice communication over an Internet Protocol [IP] network Voice over Internet Protocol (VoIP) network equipment and services H04M7/006; implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP] H04L69/16
• CPC Class Codes: Y10S 379/90 Internet, e.g. Internet phone, webphone, internet-based telephony

Abstract

A serial telephone adapter for connection between a telephone and a personal computer to facilitate voice over computer-based networks such as the Internet. The adapter also includes an interface to the public switched telephone network for conventional voice communications when the personal computer is shut down.

Claims

1. A system for use with a telephony terminal and a personal computer to provide telephone access to a computer-based communications network via said personal computer, said system comprising:

application software in said personal computer to execute an operating system program;

a serial telephone adapter connected between said telephony terminal and a serial communications port on said personal computer, said adapter having a receiver/transmitter to receive and transmit respectively telephony communications from and to said terminal, and a converter to convert said telephony communications from analog to digital and digital to analog;

a system transfer protocol to coordinate transfer of telephony communications and control messages between said personal computer and said serial telephone adapter said protocol requiring that control messages from the personal computer to the serial telephone adapter be acknowledged by the serial telephone adapter before another control message is sent; and

an interface in said adapter to connect said telephony terminal to the public switched telephone network (PSTN) if said computer-based communications network is not available for service.

2. A system as defined in claim 1 wherein said computer-based communications network is the Internet.

3. A system as defined in claim 1 wherein said computer-based communications network is an Intranet.

4. A system as defined in claim 1 wherein said telephony terminal is a telephone.

5. A system as defined in claim 1 wherein said system transfer protocol implements a polling sequence to detect DTMF tone signaling.

6. A system as defined in claim 1 wherein said system transfer protocol implements a polling sequence to detect hook switch changes.

7. A system as defined in claim 1 wherein said system transfer protocol transfers messages utilizing header bytes and body bytes.

8. A telephone adapter for serial connection between a telephone terminal and a personal computer to provide telephony access to a computer-based communications network via said personal computer, said adapter having:

a converter to receive and digitize analog signals from said telephone terminal and to receive digitized signals from said personal computer and to convert said digitized signals to analog form;

a controller to control transfer of said signals and control messages between said personal computer and said telephone terminal, said controller implementing a protocol whereby a control message from said personal computer to said telephone adapter must be acknowledged by said telephone adapter before another control message can be sent by said personal computer; and

an interface to selectively connect said telephone terminal to the public switched telephone network (PSTN) if said personal computer is non-operational.

9. A method of transmitting voice communications over the Internet comprising:

inputting said voice communications via a telephone terminal to a serially-connected telephone adapter;

digitizing said voice communications in said adapter;

transferring said digitized signals to a personal computer serially connected to said adapter, said personal computer having access to said Internet;

packetizing said digitized message;

providing universal asynchronous receiver transmitters (UARTs) in said telephone adapter and said personal computer for asynchronous transfer of control messages therebetween, wherein a control message from said personal computer to said adapter must be acknowledged by said adapter before another control message can be sent by said personal computer;

transporting said digitized signal to a selected destination in accordance with an operating program installed in said computer; and

providing said adapter with an interface to the PSTN whereby said voice communications can be transmitted over the PSTN if communication over said Internet goes out of service.

10. A method as defined in claim 9 wherein said voice message is received at said destination by a second computer wherein said signal in digital form is depacketized, transferred to said adapter whereat said digital signal is converted to analog form and provided to a second telephone terminal.