Yup, that's the most important security measure so when you "find" a phone, you can't simply do a factory reset so you can use it as your own. I know it sucks, but it's for the protection of the phone's owner, which you may or may not be because it is not stated in your original post. So, if you are the original owner, it's unfortunate you don't know the passcode and can't get into your own phone.
