NEC Corp. has developed technology that can help prevent spam phone calls to VOIP (voice over Internet Protocol) users.

The company plans to demonstrate the technology next month at the 3GSM World Congress in Barcelona but still has more work to do before it can sell a commercial product.

The technology discovers whether a caller is a human or a machine by testing the machine's capability to perform human-like conversation. Once the technology determines that a machine has made the call, it blocks the connection, preventing the user's phone from ringing.

NEC has developed the technology so that new modules can quickly be added to the system to respond to new and different kinds of VOIP spam.

In addition, the product will be customizable to work with different types of hardware, such as SIP (Session Initiation Protocol) servers, home network equipment and session border controls.

NEC tested the technology during a simulated VOIP spam attack, using well-known botnets to create the attack. The technology detected nearly all of the VOIP spam in the test, NEC said. A botnet is a collection of computers that have been infected by malicious code and can be remotely commanded to execute malicious activities.

Existing botnets can easily be modified to produce spam telephone calls, NEC said. The company warned that a high level of VOIP spam could discourage the growth of VOIP.

NEC did not say when a commercial product might become available.

The IDG News Service is a Network World affiliate.