Pioneer Bluetooth

Question

I cannot connect my phone to the bluetooth without some pin code. The phone says " enter pioneer hdd navigation pin code " but neither the bluetooth component or the head unit manuals say anything about a pin code.I have a DEH-P7900BT and I'm trying to connect my phone and Bluetooth reciever together but I can't because it keeps asking me for my unit Bluetooth PIN code. How can I by pass this question or is there another code I can use that will work????