The plan, which is part of AT&T's pay-as-you-go program, lets users pay $3 up front for every day they make or receive calls on their cell phones. Once they have paid the $3 they can get unlimited voice service for the entire day. If users do not make or receive any calls during the day, they will be charged nothing for their service.

So for example, a user that made or received voice calls on every day of a typical month would end up paying $90 in monthly voice charges. A user who made or received calls on only 15 days out of the month, meanwhile, would pay $45 in monthly voice charges.

The carrier is also offering a prepaid Unlimited Mobile-to-Mobile plan for any users who want to talk exclusively with other AT&T mobile users for $1 a day. All calls made to or received from outside carriers will cost 10 cents per minute under this plan, the company says.

Prepaid plans often prove attractive to consumers during a recession because they can be less expensive than traditional postpaid wireless plans. Last week that it saw a big boost in its prepaid wireless subscribers as it added 674,000 prepaid users in the first quarter of 2009. The downside for carriers is that prepaid plans tend to generate less money per subscriber than postpaid plans. In this past quarter, for instance, Sprint generated $56 in average revenue per user (ARPU) for its postpaid plans and $31 in ARPU for its prepaid plans.