The difference is when you pay. With prepaid service, you pay before your month of service starts. With postpaid, you use the service first and get a bill afterward. Because a postpaid carrier is extending you credit, it usually runs a credit check and may ask for a deposit. Prepaid skips that step, which is why most no credit check phone plans are prepaid. Postpaid often bundles device financing and perks, and it usually costs more, as our guide to how much a phone bill costs shows. Vouch Mobile is prepaid and monthly. The Premium plan is $30 a month for 10GB, plus fees and taxes, with no contract. You can bring your own phone and keep your eligible number.