Screenshot by Lance Whitney/CNET

Mobile phone users searching for a budget-friendly and contract-free plan can now find a few new options through TextNow.

On Tuesday, the folks behind the free texting and messaging app unveiled their own mobile phone service with plans that start at $18.99 a month. For that price, you get 500MB of data and 750 rollover minutes.

A plan that goes for $26.99 each month ups the ante to 1GB of data and 1,250 rollover minutes, while a $39.99-per-month option ramps up to 2GB of data and 2,000 rollover minutes. All three plans kick in unlimited texting and incoming calls as well as visual voicemail, call forwarding, and call display.

As the plans require no contract, you can cancel the service at any time without additional charges. TextNow also promises no overage fees should you exceed your monthly allotment. But you will be prompted to upgrade to the next highest tier.

The service runs on top of TextNow's existing IP-based text and voice infrastructure and taps into Sprint's 3G and 4G networks when no Wi-Fi is available, all of which the company claims turns it into the world's first all-IP-based mobile carrier.

TextNow's choices of phones are limited for now -- either a Samsung Nexus S for $89.99 or a Samsung Galaxy S II for $119.99, both refurbished models. The company doesn't have a bring-your-own-device option at this point. But it plans to offer that capability in the future, a TextNow spokesperson told CNET.

TextNow maker Enflick also recently introduced its own MiFi wireless hot spot starting at $14.99 a month for 500MB of data, 200 rollover minutes, and unlimited texting.

"From Day One, our biggest priority has been to make smartphone service better and more affordable for everyone," Enflick co-founder and CEO Derek Ting said in a statement. "The announcement of TextNow mobile phone service -- combined with our recent launch of MiFi -- marks a big milestone toward accomplishing this mission and making it affordable for every person to have a cell phone in his or her pocket."

Corrected 8:45 a.m. PT: TextNow does not have a bring-your-own device option but the company plans to offer one in the future.