VoIP services are now being used for the diabolical prank call practice of SWAT-ting.
Around 2002, the practice of SWAT-ting was started and gave prank calls a truly malicious side. SWAT-ters make a 911 call and falsify the identification information so that it appears the call is being made from the intended target's home. The caller reports some sort of horrific or elaborate situation, think armed hostage situations or multiple shootings, that sends emergency personnel racing to the scene and swarming the targeted person's house. The effect is understandably quite terrifying.
SWAT-ters are now exploiting VoIP service to make these calls making it virtually impossible to track or pinpoint the call's true location. Recently, some prominent conservative political bloggers have been targeted inciting 85 Republican members of Congress to take action. On June 11th, they sent a letter to Attorney General Eric Holder urging him to investigate and put an end to the harassment.
Letter sent to Attorney General Erik Holder