If there is dead air on the other end the girl is most likely nervous or trying to hear whats going on in the background on your end.
When you feel like there is an awkward pause just compliment the girl about what made you call her. This always seem to break the ice for me.
If you do have references offer them to her if she doesn't ask right away. When I know you do have them it releases a little tension. Then allow her some time to go and verify you with said references.
Once I feel that you are safe & verified, I will answer any questions that you have. Of course this is from my perspective, I don't know what other girls are like on the phone.