Make sure the dock connector is free of debris.
If you connect iPhone to an accessory not specifically made for it, iPhone may ask if you want to turn on airplane mode. This is to eliminate radio interference from cellular signals coming from iPhone. You may be able to use iPhone with the accessory whether or not you turn on airplane mode. However, the accessory may not charge iPhone.
If you turn on airplane mode, you won’t be able to make calls, send or receive text messages, access the Internet, or use Bluetooth devices with iPhone until you disconnect iPhone from the accessory or turn off airplane mode.