On the plus side, these apps are "generally reliable," said Russ Rader, spokesman for the Insurance Institute of Highway Safety.
They're also a lot cheaper than they were when they debuted two or three years ago. At the time, app developers figuring that safety was priceless, charged around $40 for their products, plus recurring fees of around $4 per month. Now, Sprint Nextel Corp. gives away its Drive First app and charges $2 per month for the service.
ZoomSafer and CellControl are two companies that offer slightly more sophisticated solutions: apps that make sure you're in your car before putting the phone in "driver mode." The phone listens for a wireless signal, either from the car's built-in electronic system or from a proprietary device that plugs into the engine-diagnostics port. The phone is wirelessly linked to the car, so people who don't usually drive the vehicle can ride as passengers without having their phones go silent. Using these apps, a driver who leaves his car behind and rides the bus won't have his phone silenced.
These apps are more difficult to set up, and more expensive. Cellcontrol charges $130 for the device that emits the wireless signal. Rader sees these as possible solutions for employers who manage fleets of vehicles and need to make sure drivers comply with the law. They may also offer some relief for parents of teenagers.