The FBI can listen to conversations on your cell phone...

[Theophylact]

...even when it's powered off:

Based on physical surveillance and the conversations previously intercepted, the FBI learned that Ardito's crew no longer conducted meetings exclusively at the four restaurants, but met also in twelve additional restaurants, automobiles, Ardito's home, an auto store, an insurance office, a jewelry store, a doctor's office, a boat, and public streets.

The government applied for a "roving bug," that is, the interception of Ardito's conversations at locations that were "not practical" to specify, as authorized by 18 U.S.C. § 2518(11)(a). Judge Jones granted the application, authorizing continued interception at the four restaurants and the installation of a listening device in Ardito's cellular telephone. The device functioned whether the phone was powered on or off, intercepting conversations within its range wherever it happened to be.

Sounds like you should take the battery out, not just turn the phone off. (Apparently even CIA agents screw up; in a recent case, agents in Italy were traced via their cell phones, which locate the nearest cellular antenna constantly even when powered down; scroll down to read in comments.)

(Hat tip to Slashdot.)

[butch81385]

Sounds like they physically installed a bug into the cell phone... That seems to be no different than if they would install a bug in your car or hidden in a plant in your house. I could be very wrong, but that was my interpretation of the information given.

[SeanC]

I bet the bug would work even if the battery was taken out of the cell phone though. Probably has a small power source of it's own.

[carl33p]

How did they manage to install the bug into the phone w/o Ardito knowing?

But i thought 'bugs' are seperate from the cell phone all together. So power would not matter.

[Theophylact]

More detail here:

The U.S. Commerce Department's security office warns that "a cellular telephone can be turned into a microphone and transmitter for the purpose of listening to conversations in the vicinity of the phone." An article in the Financial Times last year said mobile providers can "remotely install a piece of software on to any handset, without the owner's knowledge, which will activate the microphone even when its owner is not making a call."

Nextel and Samsung handsets and the Motorola Razr are especially vulnerable to software downloads that activate their microphones, said James Atkinson, a counter-surveillance consultant who has worked closely with government agencies. "They can be remotely accessed and made to transmit room audio all the time," he said. "You can do that without having physical access to the phone."

[Smidley]

I just puked a little in my mouth...

[VipFREAK]

lol, phew... good thing I'm the only one that DIDN'T get the Razr, I got a SLVR. hopefully since it's CDMA they blocked that feature too since they blocked every other feature.