As Voice over IP gain in popularity so does the number of crackers and other criminals trying to abuse your equipment for free phone calls. That is, free for them but certainly not for you! There has already been reported several incidents where companies and private citizens have had their communication bills going through the roof, $100 000 is not an unusual amount. Who is targeted? How? What equipment is vulnerable? How can we secure our ATA/phone/PBX? I’ll post articles and guidelines about this critical topic here, hopefully it will be useful to at least some of my readers!