According to the Wall Street Journal, when a cell phone is turned off or the battery goes dead, it can no longer be tracked. Smartphones also lose their tracking ability if the SIM card is removed and the WiFi is turned off.
There are a variety of programs that can assist in locating a stolen phone including Apple’s free “Find My Phone” app. A user has the ability to turn the app on after the phone has been purchased, but it must be active when the phone is stolen. Lookout mobile protection is adding a feature that will take a picture of the person who has stolen the phone as soon as it is being used and email it to the owner.