$5 bonus is coinbase account registration referral system
however i didnt see option or list of altcoins which can be used for the service
This is from their FAQ / Support:
Bitphone is seamlessly integrated with ShapeShift.io to accept Altcoin payments.
On the Main payphone, after clicking on Deposit**, you will see the Altcoin deposit button:
"Pay With Altcoins"** It actually says "Click here to deposit bitcoin".