Phone game and decent conversational skills are crucial assets when trying to progress with new girls. With many guys, the game ends with getting the girl's number because they lack these skills. Your goal when conversing on the phone with a new girl is to ultimately ask open ended questions that will allow her to convery information you can use to extend the conversation. If your afraid of saying something stupid during a convo, you can limit your talking by allowing her to carry most of the load. For example
You: Yesterday for lunch, I decided to check out this Italian resturant to see if the food there was any good. What type of food do you like the most?
Her: I like going out for Chinese on the weekends with my friends, we have lots and lots of fun hanging out. Sara and Jessica are absolutely two of the most craziest girls I've ever met in my life!
You: Sounds like you guys know how to party, but what types of things do you and your friends get into on the weekends?
Her: Sometimes we'll just hang around my apartment watching DVD's. Other times we'll go out to dance at a club, grab some drinks at a lounge or do something really fun like playing pool or bowling.
You: You bowl? Hmmm, I'm pretty sure I could beat you at that with no problems at all ;-)
Her: omg, I would totally kick your ass....blah blah blah blah (this will really get her to open up more with a playful challenge by you)
You: I see we won't be able to settle this over the phone, we're just gonna have to duke it out on the alley one night soon. (A little phone game here by hinting at a future "date". However, your initial goal should be establishing more rapport while building a comfort level with her)
Her: I guess so, you haven't seen bowling into you've seen me bowl.
You: Ha ha ha ha, yea we'll see. But earlier you spoke of your friends Sara and Jessica; where did you meet the two of them and how long have you known each?
This made up dialogue points out how you would ask questions to find out things about herself while using that info to further extend the conversation. It's not as hard as you would think, it requires actual listening so that you can properly respond to her question, answer or comment with relevent material previously mentioned.