You shouldn't go out sarging with the idea of getting phone numbers, the fact that she hesitated doesn't mean anything, for some girls givin their phone number is nothing and for some other means something "important"
What happens to most of guys is that they get flakey numbers, because all they cared about was the stupid phone number. If you want to make sure you get the right number or that she picks up the phone when you call her or reply to your text messages is to create a connection with her. Prove her that you are genuine interested on what she has to say.
Here you have a video about number closing
https://www.youtube.com/watch?v=7oga02d ... e3j7QUv6Km
This video can help you out to create a connection with her.
https://www.youtube.com/watch?v=BWeQJmd ... 4OKeDCWlQb