Republic Wireless has again opened a beta test for $19/month unlimited smartphone service.

With this innovative service, you get unlimited calling, texting, email, and web on a Motorola DEFY XT -- all with no contract. That means you pay the full retail price of $249 for the phone, plus a $29 activation fee.

Republic Wireless is an invitation-only service, so sign up today to get your invitation as a beta tester.

With junk fees, this offer works out to be about $21/month and is the absolute cheapest unlimited smart phone plan in America.

Meanwhile, Metro PCS has a new no-contract plan that's $30/month for unlimited calling and texting, plus 250MB of 4G LTE data. That works out to be $360 annually -- including all taxes and regulatory fees.

There are only eight phones you can use on the Metro PCS plan, the cheapest of which are the Coolpad Quattro 4G and the Huawei Activa 4G. Each is priced $79-$99 after rebate. Plus, you also pay a $10 activation fee on this limited-time offer.