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.

That’s changing rapidly, though. In 2003, there were only about 131,000 residential VoIP subscribers, according to the Yankee Group, a Boston-based communications research firm. By 2008, that number is expected to skyrocket to more than 17.5 million, roughly the number of people who were using e-mail when spam took off around 1995. The result could be an at least temporary resurgence of telemarketing; the Federal Trade Commission’s do-not-call registry does not restrict calls made over the Internet.

But by monitoring factors such as the length of calls and the rate at which calls are being made from particular Internet addresses, Qovia’s software can identify and block up to 95 percent of SPIT before it reaches its intended recipients, says chief technology officer Choon Shim. The company plans to incorporate the technology into its VoIP security software later this year, and if Qovia customers such as Nortel Networks build the software into their systems, SPIT may be one frustration we never have to face.