There are two numbers on the confirmation email, one is the number you provided - that is the "forward-to" number, the other number is the number to use to save money with.
https://www.inmateaid.com/ask-the-inmate/hello-i-set-up-the-discount-telephone-service-i-received-an-email-but-i-don#answer
Accepted Answer Date Created: July 07,2016