Can you take a mobile phone on a airplane?

Most airlines frown on the use of mobile devices with broadcasting functions during flight, including mobile/cell phones and handheld video-game consoles. However, most have no restriction on passengers taking a switched-off such device and its chargers, unless the flight is to an area with incompatible electronic systems, in which case assistants are advised to politely warn passengers of this if the luggage has cause to be searched.