The problem here is that once you give out a number then it's public in some sense. The person you give it to can pass it on, even inadvertently.

The smart thing to do is to have a public number and a private number. It makes no sense to call cabs with the same number you use to contact sources or whatever.

This is easily done with dual sim phones and can be taken much further with Google Voice or other dial-in phone number vendors. It's not very complicated and if your life depended on it you could easily assign a number per person.