It might be a nightmare that few of us want to imagine. But as more people abandon traditional phone lines and start placing calls over the Internet, an explosion of voice-mail spam is a real possibility, telecommunications experts say. To contain that explosion, engineers at Qovia, a voice-over-Internet-Protocol (VoIP) management company in Frederick, MD, have developed a technology that may shut up voice spam before it gets started.

Internet technology makes it easy for a single "caller" to send voice messages to thousands of people's VoIP mailboxes. Indeed, last fall, Qovia engineers managed to write software for two major types of VoIP systems that sent voice messages to 1,000 targets per minute in simulations -- the first known demonstration of spam over Internet telephony, or SPIT. Though no real-life cases of SPIT have been documented, that's largely because there aren't enough VoIP users to make it worthwhile for spammers, says Winn Schwartau, president of Interpact, a security consulting company in Seminole, FL.