The Android Open Accessory kit uses the USB port on many phones -- intended to connect to a host PC -- and instead connects it to a special Arduino-compatible board.
(Special because it has two USB ports -- a "peripheral" port designed to be connected to a host PC for programming, like most Arduino-compatible boards, and a "host" port designed to be connected to USB peripherals such as many mobile phones).
Some people think this kit is kind of a big deal.
While this doesn't directly answer your questions (it requires a USB cable between the mobile phone and the embedded system, rather than radio communication),
perhaps it's close enough.
Alternately, instead of connecting "your" cell phone with a wire and this kit to "your" embedded system, perhaps you could gaffer tape some other cell phone with a wire and this kit to your embedded system, and then communicate wirelessly using a variety of technologies between your phone and the other phone (Bluetooth, Wifi, text messages over the cell network, etc.), which relays messages back and forth.