Here’s how to emulate the telezapper by using SIT tones on your answering machine or voice mail messages…“Predictive Dialers are used by telemarketing firms to gain more ‘dialing efficiency’. About 75% of junk calls are made with a predictive dialer (PD). One thing a PD does, is monitor what happens when the phone is answered. The Telezapper can emit a ‘disconnect’ tone when your phone line goes off-hook. The tone it transmits is either a single ‘ultra-modulated’ tone or an actual set of 3 ‘Special Information Tones’ (S.I.T.) common to the telecommunications industry: depending on the setting you seletct. It works… now… in some situations. You can get a set of all three Special Information Tones from Private Citizen. Just record the tones at the beginning of your answering machine message and put your greeting right after it.” Link.
HOW TO – Emulate the Telezapper on your voice mail