First of all, let me make one thing very clear: Getting a Woman's Phone Number is not the same as having success. They may be giving it to you for a lot of different reasons, like they liked you as a friend, or maybe just wanted you to leave, or because they really felt attraction towards you. That explained, I'll show you the technique I found out that works 80% of the time.
After talking to a strange woman for like 2, 3 minutes, I say to her: "Look, I got to go back to my friends", then I turn around and pretend I'm leaving. Women are not used to men who just leave without asking for her number or whatever … So, after turning around, I turn again towards her and ask "Hey, do you have EMAIL?".
Yeah, maybe you're thinking "why the hell are you asking for email, it's useless!" … well … girls are usually not afraid of giving away their email addresses, because it does not require them to reach you so they can communicate .. so if you are a stalker, they can easily block you and forget about it …
So, after asking for the email, they usually accept. Hand her a piece of paper and a pen and say "ok, please write down your name and email address right here" … The key moment comes in now: As she's writing, tell her "by the way, write down your number too "… It works because she will already have thought" fine, he'll have my email address "and she does not see it as a harm, its just plain NATURAL to give it too.
This is my technique for getting women's phone numbers easily. Remember: you will never get it, if you never ASK. So just do it … It's actually a lot easier than you thought.