Remember that most ways to find out who owns cell phone numbers are illegal. Without the consent of the owner of the subscriber number you will not be able to officially know about it.
Remember that all operators are databases of its subscribers. If you manage to get access to one of these bases, you can easily learn all the information you need about the owner of an unknown number. But the problem is that to make formal requests to obtain information about the subscriber is entitled only to law enforcement agencies (police, FSB, FSO, etc.) or the operator itself. Look for friends in these fields. Who knows, maybe your friend working in the company-communications provider or the police will be able to help you. You should also look for database operators in selling on the black market or on the Internet. As a rule, to acquire such a database, replicated on the primitive drive that is not difficult. That's only for the relevance of the information about the required person vouch for you no one can.
If you send an SMS from an unknown number and don't want to introduce myself, you can calculate the rude caller. Try calling on undecided you have a room with another mobile phone. Most likely, you'll know who you're talking to after the first seconds of the conversation. If the messages are of a threatening nature, please save it and contact the police. Law enforcement officers will be required to establish the identity of the subscriber and conduct explanatory conversation.
Refer to the detective Agency. Typically, detectives working for private detective agencies, have a huge experience in law enforcement and will be able to help, using his old contacts. But be aware that service will cost not cheap, so weigh all the "pros" and "cons".
Ask for help on sites detectives. On the Internet you will find countless sites that offer services of this kind, both the paid and free basis. Send your details, make payment by electronic money or via SMS and receive the required information. The average cost of such services about 200 rubles.