Sounds like you need to get a Google voice # and a free "Sprint to Home" # added to your account. Then you'll have unlimited anytime to any number.
Call retentions and ask for the Pick 3, they'll tell you it's $5, tell them your friend had it added for free, they'll refuse, ask about a Sprint to Home #, hopefully they'll offer it for free!
Edit: Looked it up and Sprint to Home is also listed as $5/month
http://shop2.sprint.com/en/services/..._to_home.shtml
Never hurts to try for perks though!