I've been called twice, and I was the seller both times. The first time a buyer called me because she was waiting for her item which I honestly had just forgotten to send. I was in the middle of some serious personal/family stuff and didn't get her message right away, and she started calling me repeatedly. At one point, she even left a message saying that she knew cops in my area and maybe she'd send them over to pay me a visit. I could understand her wanting to call me, but I think she clearly took it too far.
Another buyer called me also, but this guy was just weird. He paid and I shipped his stuff the next day. He proceeded to call me every day until he received the box. Are you kidding? It took like three days to get to him and he called every day. THEN, he had the nerve to leave me a neutral feedback, citing "poor communication after shipment."
Long story short - I'd try e-mailing first or going through eBay. No one wants to get a call from some random person.