SPIT is a term used to designate unsolicited bulk messages broadcast over VoIP to phones connected to the Internet. Although marketers already use voice mail for commercial messages, SPIT 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 (CTI) but each has an IP address as well. Malicious users can harvest VoIP addresses or may hack into a computer used to route VoIP calls. Furthermore, because calls routed over IP are much more difficult to trace, the potential for fraud is significantly greater. (See also SPAM).