Well, there is a way to unlock it. Many of you probably know the way just as I do but are reluctant to post in order to protect an original owner...
With that said, I have found 2 iphones in my lifetime 3g and 4. One was unprotected (3g) and 4 was a password lock. First one was easy - called the number which said 'mom' in the favorites and a very grateful young man showed up at my doorstep 2hrs later.
iphone4, was a bit tricky, because I did not have one myself at that point (do not hate me but I was a WM guy up until last fall...), so I just took the microsim out, slid perfectly into a sim slot (a lot of room around it, but contacts were pushing it against the top rail so it stayed in place) of my daughters LG and carefully put a battery in. It powered on. Called numbers on the list via MY phone, because SIM was de-activated already... Regardless, after few tries and getting nowhere (younger kids these days) I saw an entry under 'M' said MY NUMBER... DUH... So I called it, kid (mid 20s) answered, asked him if he lost a phone bla bla bla.... When he was picking it up I asked why he never tried to call his number to locate it, he said, that there are 1 in a million out there who actually would return it, thus he did not even bother, just went to an at&t store and paid a full price for a new replacement... right after my place he said his is going back to return it ...
Point is, I made their day for sure, for both guys (one with iphone 4 did not call his parents Mom and Dad..... I asked and he said it was under their first names????? whatever, however had an urge to slap him one). My daughters witnessed both returns and I think it is a good lesson for them too. There are some people who will not just grab and run.
Just this Wednesday I found an envelope with 5 1s in it while getting out of my company car. on the envelope it said field trip money Mrs. xxxxxxx. School was 200 yards away from a place I was parked and envelope was standing up to the curb; so it probably fell out when a parent or a child where getting out and blew against it.. I walked down the street to the office and gave it to the receptionist. I felt good.
Do the right thing man and you will feel good too! do not Private Message me as I will not tell you how to bypass it - you have plenty of suggestions already as to how to make it right.