Why didn't you just tell him that you don't want him giving your number to strangers?
Its not unusual for people who have a friend they think will click with someone better and pass on a phone number. The thing is: Do you want to be passed on? Are you open to meeting this new boy? If you're not then don't answer any unknown numbers. If you are interested then, just talk to him and meet him if he seems interesting.
Go slow and only meet him in public places where your "hanging out" isn't going to lead to anything other then getting to know one another and see how well you fit as a couple.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion