Sistas with "Restricted" telephone numbers

So I met this nice young beautiful sista about 2 years ago and she continues calls me every now and then from a restricted number.  Now when I say "every now and then," I mean she calls like no more than once a month--sometimes 4-6 months apart.
Because she has not offered me her number and her number always displays as "Restricted" on my cell phone, I don't  ask her for her number.  Basically, it seems rather obvious that she doesn't do that.
So when she calls we always have a pleasant and stimulating conversation.  We even talk about going out for some eat or drink too (right...)
I did bring the issue up to her that our "correspondence was very one sided."
She asked, "How is that?"
Then I simply asked her, "Why did you call me?"
And then she said, "Because I wanted to."
Then I replied, "That must be nice to be able to do."
She just laughed it off, but I failed to see the humor in it.  Now, for my study of Sistas with "Blocked" telephone numbers, I will keep my cell phone to my ear and record how many times she calls and when.  Perhaps this will reveal more insight to this phenomenonic pattern.

Today Thursday October 24th, she called and 3:30pm.  I didn't know who it was so I let it go to voice mail and she said she'd call again later....