Question: how to pair iphone to kenwood dpx501bt?
Answer: Press the [Ú] button. "BT MODE" appears and enter the Bluetooth mode.
Use the [Control knob] to select "SETTINGS" > "PAIRING" > "PHONE SELECT" (to select the cell-phone) or "AUDIO SELECT" (to select the audio player). ... 
Use the [Control knob] to select an Bluetooth device.