Need a simple answer!!!!??????????

Question

I have an motorola C168i. I had given it to my son awhile ago & we thought it was lost never to be found.Recently during a move we found it & I was planning on giveing him another chance,but some reason when you turn the phone on it says "Phone Lock Code:" I have no clue of what it could be. I've tried 0000,12345.etc.... I can't seem to remember which # in my address book goes to this phone since theres so many #s that have come & gone. Please help me & him. I see no reason why I should pay for the code its self since I have spent $ on the time to put on it & also the phone itself.Not mentioning all the phones I purchased of motorola products.You can contact us on my sons yahoo.com. Thank You. Coles Mom