I have used this calling card for the past 10 years.
They offer great calling rates for both home 800 numbers, and calling cards.
Now they have even lower rates than before.

13.9¢ Best Rate Calling Card / 6.9¢ per minute Personal 800 Number Service
6.9¢ per minute Long Distance and ULTRAnet Internet Access with great rates by:

 American Telecom Network SM

American Telecom Network

Lowest rates, and no application fees, deposits or hidden charges.
There is nothing to loose.  Click on the link above for more information.