Wal-Mart has long offered prepaid mobile calling plans for thrifty customers, but now it’s venturing into new territory: post-paid cell phone plans. Wal-Mart coined the term "post-paid” itself in a conscious effort to sidestep the stigma of the much loathed "contract” cell phone plan. Traditional contract-based cell phone plans have received countless consumer complaints and even FTC criticism over their restrictive (and sometimes downright punitive) early termination fees and overage penalties.

As an alternative, discount cell phone plan providers—such as Wal-Mart—began offering no-contract plans where minutes were purchased upfront, thus preventing unanticipated charges for going over a monthly limit or cancelling service. For heavy cell phone users, however, an unlimited calling plan may be more economical than a prepaid plan. Plus, unlimited cell phone plans don’t carry the risk of running out of minutes unexpectedly.

Wal-Mart’s post-paid cell phone plan, which was announced earlier this week, is an attempt to bridge the gap between prepaid and contract phones without taking on the drawbacks of either billing scheme. Like a contract phone plan, Wal-Mart’s post-paid cell phone plan features monthly billing and unlimited calling. But the post-paid cell phone plan does not come with a contract, thus can be terminated at any time without incurring penalties. Furthermore, credit checks won’t be required to open a new account.

There are still some considerable costs associated with the post-paid cell phone plan from Wal-Mart. One of the perks of a contract cell phone plan is the discount or free phones customers can obtain when signing up for a new account or renewing a contract. With a post-paid or pre-paid plan, consumers are often saddled with the full retail price of the phone. Also, Wal-Mart’s post-paid cell phone plan does not include unlimited data. Data plans, which are required to access the smartphone features in devices such as the Motorola Cliq, start at $10 for 200 GB and range up to $40 for 1 GB of data. Unlike monthly data allotments, data purchases "roll over” month-to-month.

Wal-Mart’s post-paid cell phone plan may be a good fit for cell phone users who place numerous calls each month and text often. But this move may be the most significant in terms of pioneering new ground in cell phone plans. Depending on the success of Wal-Mart’s post-paid cell phone plan, we may see other companies waiving contracts and early termination fees.