Here’s how the phones work.
You buy the phone outright. It costs about $10. Then you buy a minutes card that goes along with the service. You follow the instructions on the phone to add the minutes to your account. Your phone is then active until the minutes you added run out, then you have to buy another card and add it.
Some prepaid phone services are tracphone (my favorite), boost mobile, virgine mobile, cricket, etc. Minutes cards usually start at $10 and then go up from there. 🙂