There’s yet another new scam out there: You get a call to your phone and it rings once. You don’t recognize the number but you think, maybe it’s a business call or something important, you call it back just to check. This could cost you money.
The number may be a premium number, meaning that you will be charged a fee for every minute you are on the line. Remember the 900 numbers for dating services, etc. that use to be advertised on TV. This works the same way. Now the numbers are no longer so obvious as to begin with 900. You can find a full explanation by the BBB here.
Bottom line: if you don’t recognize the number, don’t call back. If it was really important the caller would have let it ring more than once, or they might have tried to call back, or they would have left a message. If you still think it might be legitimate google the area code, that should tell you if it’s coming from a real place or if it’s a premium number.