Will awkward phone calls ruin the chances I have with the girl I like?

It seems when I'm alone with her or we're talking online that I'm the smoothest cat there ever was. A real charmer. But as soon as I talk to her on the phone (we've only talked three times on the phone.) I become SO awkward. My personality is GONE. I hate talking on the phone. But I hate texting even more. Also, she's really hard to approach because she's always with her friends. She's a senior and I'm a sopre. But when we hang out alone or whatever we both seem really interested in each other. I'm very suave in person, but calling her is quite the opposite. I've talked to her on the phone and it's been REALLY awkward. And one or two times in person it's been pretty awkward. But the other times are just fine. So what are my chances with her now? And how can I hopefully raise them?