Cellphone users sent more than 158 billion text messages in 2006 -- a 95 percent increase over the previous year -- according to CTIA, an international association for the wireless telecommunications industry. Taking advantage of the enormously popular function, the Boston Police Department launched an anonymous text-message based crime tip line June 15th. The Text a Tip program, the first of its kind in the nation, gives the most active texters -- teens and 18- to 24-year-olds -- a familiar and discrete channel to report information about a crime. To report a tip, citizens need only text the word "tip" to C-R-I-M-E (27463). The system, powered by VeriSign, masks all personal information before sending any text-messaged information. Through an interface, BPD can immediately exchange messages with the tipster to obtain more details. Since it opened, it's been a huge success, leading to two arrests and several leads. Anonymous tipsters have tapped out some 230-text messages to the Crime Stoppers unit so far. By comparison, the unit usually gets only about 10 phone calls a month. Several cities, including Tampa, have launched or are in the process of launching a similar program. To learn more about the Text a Tip program, click here.