the more you call, the more you look like a wuss and women hate guys who are wusses!
DON'T DO IT, EVER
you're best play would have been to not swap phone numbers ( so old fashioned) but emails because that way you can keep in touch much more informally
but since you did have her phone number, you should not have left a voicemail but sent a quick text message that you are going out with friends for drinks on some future non-prime-time night (next Tuesday!) and ask if she has time to join you
that way you look like you have a life and throw the ball in her court to either decline or suggest something else (if she is truly interested, she will)
by calling her back you may have already proved to her that you're just like every other desperate guy, but for your sake I hope not