There are a few ways in which you can try to find out who owns a telephone number. The first step you should take, as a long shot, just type the number into Google and hit search. Luck might be on your side especially if it's from a business number, or if the caller has put their phone number on a website somewhere. Your next stop should be a free reverse phone number directory. Sometimes this can be enough to get results, and you don't need to go any further. Generally they all use the same databases, so if you don't find the number at one, then you're very unlikely to find it anywhere else.