Voice to Phone Advertisement over VoIP, or SPIT (Spam over IP Telephony), is a security threat with the potential to fill voicemail boxes with unwanted messages in much the same way that spam currently fills many email inboxes. With toll costs low and access open in many VoIP environments, advertiser are theoretically able to record an advertisment once and blast it to many using nothing more than a PC.

As more telephone traffic moves onto the Internet, attracted by its low costs, so too will the sales pitches of telemarketers. And just like e-mail, individual Internet voice messages can easily be sent from one to many.

Although marketers already use voice mail for commercial messages, IP telephony makes a more effective channel because the sender can send messages in bulk instead of dialing each number separately. Internet phones are often mapped to telephone numbers, in the interests of computer-telephony integration but each has an IP address as well.

SPIT is not much of a problem yet, simply because IP telephony is not widely used. However, experts expect that the technology will become increasingly common over the next several years, thus making it much more attractive to advertises.