Do not call her again. She will not pick up - she either 1) knows it's you and does not want to talk to you or 2, more likely) doesn't recognize your #. Don't give her your # - she won't call, women rarely do unless they're aggressively pursuing you - I think we all know this is not the case here.
For the last g0dd@mn time - ASK HER OUT IN PERSON! She cannot screen your call this way. This is most DIRECT approach possible. I know it's a scary prospect, but what have you got to lose? No guts, no glory! DO IT TODAY!!!!!
If only I had known what pusses boys were back when I was in my 20s!