Do you live together?
How often do you see each other?
What do you nag him about?
It's so typical for women to want to sit on the phone and chat for hours, most guys don't work like that. I take it as a good sign that he doesn't mind talking for a few minutes here and there all day, at least he's not blowing you off, he just may not be a phone person.
What you have to do is find a middle ground that you are comfortable with. If you're 'nagging' it's usually an indication that you're unhappy about something. If that's not addressed it will only get worse. Maybe you can compromise and talk once a day for an hour or once every other day for an hour. If you don't see each other on the weekend, then you definitely should get more phone time. Basically you are a phone person, and he isn't so you have to find a comfortable middle ground for the both of you.
There's no sense in getting jealous, maybe you need to pick up a hobby or take a class. When you have one really busy person and one that's not as busy, then one can get jealous because they think the other person doesn't have time for them. This is not necessarily the case, but sometimes adding a thing or two to your own schedule can help distract you from wondering about him or being lonely. It's natural to feel this way so don't beat yourself up about it. You just want to be wary of pushing him away because of feeling jealous or insecure.
Look at the good things and remember that thru out the times that you are not together. Be honest with him about how you're feeling, even if you think it sounds silly, it at least lets him know how you feel inside.
I welcome your thoughts, let me know if you want to talk further.