Call me old fashioned but I believe it is the man's job to call. This goes back to my previous post but I will not chase after a man, I believe a woman's job is to send signals of interest and receptiveness and allow the man to do the rest of the legwork. I'm not saying I'll never go after a guy, but generally I won't.
I believe that when you are casually dating the intial conversations should be limited to thirty minutes a day, maybe an hour every other day (at most). But no, I won't sit with a timer! A text message is nice, but only if it's non-conversational in nature ("Hope you have a nice day," "You're hot," etc.)
Phone calls are like mind-foreplay to set the energy for the date. Sure, talking all day and night with your crush is great for instant gratification. But if you want it to go somewhere, you have to build anticipation. Think of the dates which you were looking forward to, weren't you nervous? The nerves are part of the chemistry, by getting too comfortable too quickly you skip that entire stage. All the sudden the first, second, or third date doesn't feel like a "real date" anymore, but just like any other phone call except face-to-face.