Don't worry about making a good impression on the phone. Why? Because she should be making a good impression on you. Now to get a convo going just expand on little things she says and get her talking.
You: Hey wassup
Her: Nothin, what about you.
You: Nothing really, wat did you do 2day?
Her: Well i had to stay after school for play practice cuz I got the leading role.
You: What play is it (you are expanding on what she said..)
Her: (sum play, had the word tree in it)
You: Oh so you are the tree in the middlle of the stage?
Her: No!! (giggling)
Just go off like that. I got her talking about the play for a while and she said something about gettin' a puppy, but we kept talkin' about the play since it was just a little sidebar. Once we were done talkin' bout that I felt an awkward silence about to come on, so I asked her about the puppy. BAM! Just get her talkin' about something, and chicks will go on forever. Try not to get into depressing topics though.
Now sometimes you get stuck with a flat out boring chik..
You: Hey wassup
Her: Nothing
You: What didja do 2day?
Her: Nothing
You....
Doesn't give you much to work with, does it? Whenever that happens though, I just say something like "Don't go too crazy there party animal" and if shes really pissin' the **** outa me I'll flat out tell her "You are puttin' me to sleep here, I called so you would entertain me". If you are runnin' outa stuff to talk about a good one I always use is which gender has life harder. I think it is a fun thing to talk about. Think of fun stuff like that so you have something to bring up whenever you are outa ****.
Her: Girls have it so much harder! We have PERIODS!
Me: Guys have it harder.. We gotta deal with girls on their periods.
Me: