For example, if you find a wallet, looking through it for some form of identification belonging to the owner, such as a driver's licence, would be considered a "reasonable step". Likewise, with an iPhone, if you can access the contacts, look for an entry labelled Home or ICE (In case of emergency) and then try calling the number.
Chances are however, if the owner is tech-savvy they may use the Find my iPhone function to discover the iPhone's location and then send messages to the handset asking for it to be returned. If you're concerned about your own iPhone, here's how to set-up and later locate your handset using Find my iPhone.
It's very likely that the iPhone's owner will have contacted their network with the IMEI number of the handset. The network will have put a block on the device making it unusable or 'bricked'. Furthermore, if the owner has been using the Find my iPhone service, they'll probably have also used the remote wipe function to remove all the data, apps and contacts from the device. When you turn the smartphone on, it'll probably say 'iPhone is disabled' in red at the top of the screen and you'll be unable to access any features or function, even if you connect it to a PC.
So what should you do you have now? You could sell the device on eBay labelled as not working for a fraction of the cost of a new device

ho ho

upali ga i čekaj, možda se vlasnik sam javi. imeniku nemožeš pristupiti, razumni razlozi englezima nisu policija.. a bome ni u našoj državi. ako se nitko ne javi par mjeseci, rastavi ga.