My experience has been that calling a sponsor every day is meant as a way to develop trust, as well as a way to learn how to follow directions - a pre-cursor to bringing the sponsee through the steps.
So, in my case, it wasn't about having 'meaningful' conversations every day, but more about establishing and following a routine.
I didn't mind trading voice mails as long as I knew I was doing my part by calling her (and I didn't expect to reach my sponsor either - that helped - nothing fuels resentment more than an unfulfilled expectation).
That said, it was important for me to meet my sponsor f2f once a week though. There has to be some kind of consistent communication between a sponsee/sponsor in my opinion.