Can anyone tell me about pre-paid phone calls? I found one and sent them the information that they needed but I never heard back from them. Does anyone know of any companies that do pre-paid collect phone calls?

It depends on whether you are talking about Cell phones or land line phones.
PCO (Prison Calls Online) does prepaid for Cell phones. The rates depends on how far you are from the prison, and also whether they are set up for that prison or not.
MCI does pre-paid for land line phones. You can actually set a limit for yourself. Say, 100.00 a month for collect calls. You pay them in advance and they set you up each month. Once your limit is reached, you either pay them again, or wait until the following month, depending on how you have it set up.
You can get this info by going to the prison calls forum.

PCO is the way to go on the pre paid... I signed up last month, and it's been really great. Way cheaper than regular collect calls. They can set you up on a land line even if it is blocked, or your cell phone. Go to their web page, and when you request service they'll send ya an application via e mail.