Having just received my Cingular Treo 600 and using it with my T-Mobile account, it looks like I should add the internet plan to my T-Mobile plan. The problem is that right now I don't actually spend that much time on my phone, 20-30 minutes total per month.

It looks like I could just get the Internet Plan for $30 per month, and they charge an additional $.20 per minute for phone calls. Is anyone doing that, with no other calling plan, with T-Mobile? Given my limited phone usage, that seems like it would be the best deal.