Thank you nchto. I don't think it's my VOIP provider though. Here's how I came to that conclusion:
800-521-2232 is Duke Energy's call center. It's answered by an auto attendant if you wanted to try it yourself...
The guy at the desk next to mine uses a desk phone to make calls over our VOIP network. When he calls 800-521-2232, he hears two rings then the auto attendant.
When I call on my cell phone, I hear one ring then the auto attendant.
When I call using express talk, I hear many rings, followed by a timeout error.
Any ideas? Thanks again.