Yes google talk is not what it was.
You have to sign up, meaning log in with your gmail account from your phone
sign in and add number to your account.
You can either add a new number for Gvoice or use your existing cell phone number.
Once you do that you have the option to add money to your account for making phone calls....
OR to do what you would like.
Get GrooVeIP, which is a VoIP apk that uses google voice and you can make calls without needing to add credits!