I've been reading some material on direct approach, and here's what the guy has to say about asking/giving phone numbers:

"Traditional dating advice, as well as PUA advice tells you to ask for a girl's phone number. However the problem is that women give out their phone numbers like candy these days now that everybody has mobile phones, so phone numbers literally mean nothing any more. A lot of guys believe that getting a girl's phone number means they've pulled her or it's some sort of indicator that she's interested in him romantically/sexually. Nothing could be further from the truth. A phone number is just a way to get in touch with someone, that's all.

Girls give out their number to tons of guys, and have guys calling and texting them constantly. It's just a free ego boost to them. What I've personally found to be far more effective is to give a girl my phone number instead. Usually I have some business cards on me whenever I'm out, and when I approach a girl, I will hand her my business card and tell her to call me if she's interested in getting together. After that, I say goodbye to her and go about my usual life.

So giving out your number is a great way of doing things because you've approached the girl, you've been Direct with her and told her honestly what you want from her/what your true intentions are, and now you've given her your number and told her to call if she wants to get together with you. So you've put the ball in her court; she knows the score and she has a way to contact you should that seed in her mind grow about you and her getting together romantically/sexually.

Also, by not calling her there's a sense of mystery about you. You will not be like every other guy who calls her or texts her all the time, and because of that and because of the bold Direct approach you did, she's going to remember you and think about you a lot before she contacts you. You are a guy who has your own busy life going on (you do, don't you?), and if she wants to enter your world she's going to have to come to you.

Which brings me nicely to the last point. By giving her your number, you put her into a position where she has to call YOU if she wants to get together. In other words, she's got to work for your attention, and this naturally makes you a challenge and makes you stand out from other guys. When she calls, you will be in the power position and have the upper hand.

The other great thing about giving out your number instead of taking girls' numbers is that it automatically weeds out which girls are genuinely interested in you vs the ones who are not. You see, if a girl calls you after you've approached her like this, she's almost certainly interested in you romantically/sexually. And if a girl doesn't call, well that's fine too because you didn't waste any time or money pursuing her."

What do you think?