It is a scam.
They direct you to "log into your cell phone/telephone account" through their link for the free money.
All you are doing is giving them access to your account.
With that info, they can sign you up for dozens of fee based services, use your account to purchase items, or run up your phone bill with calls they authorize.

Goatt203.com said I had a $203 credit on next month bill. Seems like a scam.