Matthew Weigman, 19, was part of a group of telephone hackers that met up on telephone party lines and was associated with more than 60 "swatting" calls to 911 numbers across the country. Weigman, known as "Little Hacker," became involved in telephone hacking around age 14 and continued to operate until last year.

Swatters make prank 911 calls, but they use spoofing technology to make it appear as though the call is being made from a victim's house. The idea is to harass their targets, preferably by having police show up at their door, guns drawn.

Most of the members in the group have already been sentenced, and Weigman was given the longest sentence. He was arrested in May 2008, shortly after showing up at the home of a Verizon investigator who had been building a case against Weigman and the other swatters. Weigman, his brother, and another swatter named Sean Benton drove nearly 70 miles to the investigator's house in order to "intimidate and frighten him," the U.S. Department of Justice [DoJ] said in a statement Monday.

But the gang saved their really frightening swatting for others. On June 12, 2006, for example, another swatter, Guadalupe Martinez, dialed 911 using a spoof card to make it look as though he was calling from an Alvarado, Texas, phone number and told dispatchers that he was holding hostages and had killed family members with an AK47 while high on hallucinogenic drugs.

A single SWAT (special weapons and tactics) incident can eat up tens of thousands of dollars in emergency services costs, and it can be dangerous too, when victims suddenly have to deal with armed police officers.

Weigman used his skills to target "employers, landlords, families and friends of multiple party line participants," often in the hope that they would be fired or evicted from their homes, the DoJ said. Sometimes he and his group would cut phone lines, or listen in on victims' conversations.

Weigman and his crew used a variety of tricks to hack the phone system. They would trick phone company workers with "pretexting" calls, where they pretended to be employees or customers in order to obtain information; they would try war-dialing -- using a computer to dial thousands of phone numbers in hopes of gaining access to a system; and they would also trade passwords and information with other telephone hackers, known as "phreakers."