Phone numbers

I've been thinking about how women are sometime reluctant to give out their phone numbers to strangers, and I came up with an idea. What if there were temporary phone numbers that would mask your real phone number for as long as you choose? A woman could meet a guy, give him a temporary phone number and if after a few calls he turns out to be a psycho, she disconnects that phone number and he never bothers her again. As simple as that.