i think it might be good to jus tell her honestly your intention...of cos not telling her you want her to be your gf lah...but jus tell her that you want to talk wif her to get to know her more. and you can actually tell her honestly that you feel nervious every time you call her...i think gals appreciate honesty and sincerity.
last time, i also got to know a gal and got her phone number oso. was jus as nervious as you i guess...but i jus told her honestly that i am feeling quite nervious but i really would like to get to know her more. and she agreed
i was so happy then.....
well thou we din end up together...cos we found out we arent suitable for each other....but we are still good frens now...i still call her, even go out wif her....but jus as a fren
so give it a try...if she agrees like my fren....then you can one step closer