If you are not talking to her how are you to establish a relationship? I know you're to keep a level of "mystery" involved, but you got to chat with her at SOME POINT. The telephone/AIM was made for the use of one thing: comminication. The more you talk to her the more trust she will have for you, that is the basis for a relationship is it not? Quick chats on the phone/AIM are good, very intimate, not as much as in person where you can use kino, but still effective. Hell you can use it to test how far you can go with her regarding what you talk about or say to her. If you say something suggestive or something she finds offensive or doesnt agree with the aboslute worst thing she can do is hang up on you, and you learn how to communicate better this way by thinking before you speak, learning comebacks and how to handle certain situations.
I'd use the phone/instant messenger for these
1) Setup a date
2) Casual conversation for a couple min
3) phone sex...jk
The best conversations are when you are in person for you can develope a familiarity with the chick. However, you might feel insecure because she's looking at you, seeing how you dress, talk, carry youself, blah blah blah. That's the drawback for in person convo. Jus stay relaxed and in a good mood. Remember to keep the topics positive and not TOO deep. Have fun with it and pimp on.