Several months after shipping handsets to its first batch of testers, Republic Wireless has announced it is re-opening signups for its beta program and offering customers a new smartphone option. The Wi-Fi-centric mobile operator, which offers ‘unlimited’ talk, text, and data for only $19 a month and no contracts, will now carry the Motorola Defy XT for $249 in addition to the old Optimus S it had been using.

For those unfamiliar, Republic Wireless launched late last year promising bargain prices compared to established wireless providers by heavily relying on Wi-Fi networks. The company bakes in proprietary “Hybrid Calling” technology into its phones, forcing them to utilize Wi-Fi networks when available, and falling back to conventional WWAN via a partnership with Sprint the rest of the time. Unfortunately this means having a very limited phone catalog (just two at this point) but more will be added in the future.

The company estimates that mobile users are around Wi-Fi about 60% of the time. They initially planned to limit how much cellular data its users could consume based on a "Cellular Usage Index”, but the company quickly changed its terms to say that unlimited service would be truly that.

The new Defy XT being offered is a rugged device featuring dust/water resistance and comes with a 3.7-inch display, 1GHz processor, front (5MP) and rear (3MP) facing cameras, 512MB of RAM, 1GB of internal storage. It’ll cost $250 upfront, and though that seems a little steep for an Android 2.3 “Gingerbread” handset in 2012, keep in mind that you’re getting it with no contracts attached.

It's unclear when Republic Wireless will bring its service out of beta for a full on public launch, but they seem to be making steady progress. You can hop in queue for the beta by registering here.