Honestly, IMO you want to keep the phone conversations short in the beginning. I learned its best to make calls only to set up dates. Your goal is to get her in the sack

. You have to build sexual attraction and this can escalate much faster in person then over the phone. A quick 'alright so ill meet you at 9 over there, don't be late or ill spank you' kinda thing is what you wanna limit your phone calls to. This isn't a one size fits all though, especially if you've never met this girl in person yet, so before you build attraction, you'd obviously want to let her be assured you are not some creep and that she will be safe meeting you in person. Later on you can have the hour long talks once you've built chemistry, interests etc.