The easiest way to find out who was phone, it is to refer the matter to the operator. Here only queries of this kind can officially do only the police and several law enforcement organizations of a higher order, such as the FSB, FSO, SVR, etc. What do mere mortals that do not have friends in such circles. Try to find outlets for employees of companies-operators of cellular communication. Although they are not allowed to disclose information about subscribers, all for a reasonable fee they can go with you to compromise and help. As they do, not your concern. Most importantly, you will receive the required information.
You can use "Ruse" and to contact the operator directly. For this you will need acting skills, and a bit of improvisation. The fact is that when you pay for communication services, operators are visible to the personal data of the payer. This information can and should be used if you want to find out who registered the phone number. Make compassionate face. Go to the payment of cellular communication, which now can be found on every corner, with the advance of invented legend. For example, you can tell the Manager receiving the payment for communications services that your best friend who is now in business trip, out of money on the phone and you would like to replenish the balance. A matter of life and death. But only the last digit of the phone you forgot. Make pleading eyes and ask for help. If you will be good to bluff on, the operator will give you the required information - surname, name, patronymic of the subscriber. If you come up with some more excuses, you can extract other information. But it is up to you. Remember that the important thing is that your legend was plausible. What to do if the Manager of the cellular interior you will be denied? Right, go to a nearby place where they take payments for mobile communications, and repeat the procedure.