I found an iphone, how can I unlock it?

So, a few months ago, I found an iphone at work, I turned it into the lost and found and no one has claimed it since. My boss gave it to me since it has been upwards of three months and no one has come looking for it. I checked the SIM card slot to see the carrier, but it was empty. Its a password protected phone, so what can I do to unlock it? Is there still a way to contact the carrier without a SIM card? I have zero experience with apple products and have no clue what to do here. Obviously if there's a way to use it as my own if the owner can't be found I will, if they can, Id like to return the phone. What can I do to either unlock the phone or track the owner/carrier?

Start by contacting the police and Apple.

Go on your iTunes and reset it, it will tell you the name of the device, you'd find someone's name there anyway.

You could get it unlocked from factory unlock service, but if the original owners have barred the IMEI number then that won't help you.

Best thing, is contact Apple as they should be able to track down and contact the original owner.

Well if you want to return the phone, first you may need to unlock it http://theaffordablecellphoneaccessories.com/cheapunlockedGSMcellphones.php.