Here's the Bronx Cheer for IDT: f-ff-f-f-f
These guys WERE great. 6.9c/min, with a 0.99 fee per month for their dialaround service. Look closely at your usage rate, though. I began to find that my cellphone was being charged as a PAY PHONE, with $0.85 added on to every call, completed or not. Calls to IDT, (requiring a 20 minute hold) were met with "we can't do anything", etc., and "nice, concilatory" gestures like removing the last 3 charges (big deal if I have to spend 2 hours a month of my time on this). Then, they raised the monthly fee to $1.50 with no notice, and twice, I've been changed to a higher rate (each time they happily changed it back ONCE I SPENT 20 MINUTES ON HOLD and then told them it was wrong).
Sheesh; too busy for this. I can't possibly recommend them to anyone until they clean up their act.