What is the cheapest route to take for phone calls?

I do not think there is a cheap route. I have used Correctional Billing Service. I do not pre-pay, I have it charged to my phone bill. I checked on other companies but did not find a better rate. Something new came to my attention today. The Yahoo messenger offers a phone line you can get and have a number close to the facility. Log on to their website. I think I would have done this if I knew about it earlier.
South1