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C2 (formerly Acceris)


C2 (formerly Acceris)

Patent Busting Project
An EFF Initiative To Protect Innovation and Free Expression


Crimes Against the Public Domain

  • Overbroad patents cover nearly all current implementations of VoIP, an emerging technology, thus stifling innovation and use of VoIP as a tool of free speech
  • Crippling the progress of small VoIP developers could undermine ease of communication online

Prior Art Description

Latest Date That Material Can Qualify for Prior Art: September 20, 1995

I. General Description

The Acceris patent claims a "Method and Apparatus for Implementing a Computer Network/Internet Telephone System." The patent was filed on November 1, 1995 and granted on June 5, 2001. During prosecution of the Patent, an affidavit was made that the invention was conceived as far back as September 20, 1995.

The primary example used in the patent is phone to phone communication using both the public switched telephone network (PSTN) and the Internet:

The patent attempts to claim a range of Internet telephony applications. These include a method and apparatus for using a public computer network to route a full-duplex telephone call, where a telephone connected to the public switched telephone network ("PSTN") is at the receiving end of the call. Put more simply, the patent claims to invent calling someone at his or her telephone number, where the call is routed at least partially through a computer network such as the Internet rather than completely through the PSTN.

II.The Claims at Issue

There are 24 claims in the '373 Patent. However, Claims 1, 2, 5, and 6 cover the essential aspects, so the descriptions below focus on those claims for busting.

Claim 1

Claim 1 covers a method for routing a telephone call between two telephone sets where part of the communication link is made over a public computer network. The telephone call is placed from one ordinary telephone and the user only has to dial the destination number without specifying or dialing any additional numbers. The call is routed from the provider's central office and during that process, the data is converted to an Internet protocol and sent from an access port at the central office to a remote access port. The data is then converted to a PSTN protocol and a phone call is routed from the remote access port to the destination number.

Claim 2

Claim 2 limits the method of Claim 1 specifying that the first telephone call is routed via a PSTN at the central office.

Claim 5

Claim 5 limits the method of Claim 1 specifying that the first telephone call is the only call placed. This probably means that the second phone is connected to a PBX with the special internet routing technology built into it, such that it converts from an Internet Protocol to voice data at the location of the phone.

Claim 6

Claim 6 limits the method of Claim 1 specifying that the computer network is at least a portion of an Internet computer network.

III. Description of Prior Art Needed to Bust the Patent

To qualify, prior art must have been publicly available before September 20, 1995. In order to invalidate the entire patent, we will need prior art that covers each claim. (See Critical Features of Prior Art Needed below for the specific prior art needed)

As described above, the patent contains both method and system claims. A method claim covers a way of doing something, like a recipe, and a system claim covers a tool for doing it, like a product. For this patent busting project, prior art that shows either will help us defeat the claims.

Any publication (an article, software code, a web page, a patent, a conference poster presentation, or other public writing) or a product can serve as prior art. The prior art should cover all aspects of a claim to defeat that claim. Prior art for a dependent claim must include all aspects of the independent claim that it's based on, as well as whatever the dependent claim adds.

We would like to demonstrate to the United States Patent and Trademark Office ("USPTO") that the method and system for which they granted this patent was not novel. For this reason, we are looking for "prior art," which is conclusive evidence of the existence of a similar product, method, or idea before September 20, 1995. Equipped with the right prior art, the USPTO may declare the patent invalid.

Specifically, we are searching for evidence of the creation, description, publication, or announcement of products or processes that exhibit all the "critical features" listed below. We are also searching for evidence of "additional features" listed below. Such information must have been publicly available before September 20, 1995,or earlier in order to qualify as prior art. For example, a May 1995 whitepaper on Internet telephony might qualify as prior art.


  1. The system must have the ability to connect an audio telephone call from a calling party to a receiving party.
  2. The telephone call must be "full duplex," meaning that both parties must be able to talk and listen at the same time. For example, regular telephone calls usually are full duplex, whereas walkie-talkie conversations in which a person cannot receive transmissions from others while he or she is transmitting generally are not.
  3. An ordinary telephone and telephone line are the only equipment the receiving party needs to have. The receiving party does not need to have a computer or an Internet connection to receive the call.
  4. The transmission of the call is routed in part through a "public computer network" and in part through the PSTN. This implies that the transmission must cross at least one gateway between the "public computer network" and the PSTN. The Internet is one example of a "public computer network," but the patent does not define what else would qualify as a "public computer network."

Additional Features:

  1. The caller must only have to dial the destination number and no additional phone numbers

UPDATED: It has come to our attention that patents describing a call to be made using a telephone to another telephone using a "packet-network" and specifying only one destination number exists. It would be helpful, if any public information is available near or between September 20, 1995 and March 5, 2001 that equates a "packet network" to a "public computer network" or the "Internet".

We have also identified and listed below several products from the mid-1990s that might fit the above criteria. Information about these as well as any other products would be greatly appreciated.

  • Net2Phone. According to its website, Net2Phone is a product that enables individuals with computers and Internet connections to place voice calls to anyone with an ordinary telephone. We are looking for documentation about Net2Phone that predates September 20, 1995 or evidence of Net2Phone's existence before September 20, 1995.
  • Internet Phone by VocalTec. VocalTec's Internet Phone was one of the first commercial software products that enabled audio calls between computers on the Internet. According to a 1996 trade journal, VocalTec planned to enhance Internet Phone by releasing a gateway that enabled online users to call anyone with an ordinary telephone. We are looking for documentation about this gateway functionality that predates September 20, 1995 or evidence of such a product's existence before September 20, 1995.

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