There are many sites online that will tell you if a mobile number is active or not. Unfortunately, these sites are a hoax and they don't work at all. They can try and give you a rough idea of the number and where it is from or located. There are also sites online that you can do a reverse phone number lookup and see where the number came from. I don't think they will tell you who owns this number, but you can find out where the number is located.
Trying to find out this information is basically against the law and you can't get the information. You don't have much choice in this matter except to call the number and see what happens. Furthermore, you can try sending a text message to the phone number and see what happens. Other than this there isn't much you can do to find out this information. If this was your phone number in the past or a number that you want to get, then you'll need to call the cell phone provider to see if this number is still available.