Try to break a cell phone number online through search engines. If it belongs to fraud, the more likely you will see it in one of the relevant bases with the description. Attackers often mask a number of mobile network operators, various services, entertainment, etc., resulting in subscribers that have already become a victim of fraud, post them online to warn other people.
Please note the first 3-4 digits. If he does not begin with the code "+7" or "8", then, most likely, was abroad. The next 3 numbers after the code can you tell which mobile operator owns the room, and in which region or city is its owner. You may take this combination through the search engines and find out how safe are calls in the room and how much they would cost.
Subscribers often publish their numbers on various resources, such as social networks, ads, job search, Dating, etc. Thus, when using search engines quite a high probability to find a link to the page of the phone owner on the Internet. Try also to break the cell phone number through the mentioned resources because they also have an internal search engine that lets you search for people according to various parameters.
Check out the websites of mobile operators. Some of them offer special paid services by definition the owner and the location. Please note that while the owner of the phone will be aware of your actions, and as soon as you try to break a cell phone number, he will receive the corresponding notification, which may reply with acceptance or refusal.