Start with the simplest and legal way to identify the owner of the phone by his number - call him. Maybe you're lucky, at the other end picks up, and you can find all the necessary information directly from the first hands. Remember that the phone can come and relatives that will also facilitate your search. Ask them the coordinates of the owner of the room.
Buy in the market where they sell electronics, database operator, whose room needed to break through. Enter in the appropriate fields of the interface, cherished numbers, and you will receive the contact information of the person to whom it is registered. Using this method of obtaining information, keep in mind that the older the copy you purchased the database, the less reliable the information you get when it is accessed. Also be aware that subject to such database by legal means. When you access this database you are in violation of article 137 of the criminal code "Violation of inviolability of private life".
Find out who registered the room right at the point of payment of communication services. The fact that the Manager when crediting funds to the account of your mobile phone see information about its subscribers. It's just the same information that you used when signing contracts with your Telecom operator for provision of telecommunication services. Naturally, the Manager has the right to disclose this information under any pretext. But knowing what the situation is happening in practice, you can still try applying a small trick. Try to soften the Manager, citing unforeseen circumstances or just offering him some money. You may be able to obtain the information you want with little bloodshed. If you are denied, you do the same in another salon of cellular communication, since they are now on every corner.