Angela Lang/CNET

For the last couple of years, Mint Mobile has courted new customers by offering low rates -- but with the stipulation that you have to buy service in bulk, prepaying for anywhere from three to 12 months. For example, a $240 payment will buy you 12 months of the carrier's 8GB plan.

Now, if you're willing to pay just a bit more, you can get a similar deal from AT&T: The online-only AT&T Prepaid 8GB Promo Plan costs $300 and buys you 12 months of service. (Taxes and fees are extra.) That's literally half the price of the same plan charged monthly.

Just a heads-up: The links above may take you to an AT&T page that offers several different packages. Make sure you scroll down and click on the one that offers the AT&T Prepaid 8GB Promo plan.

I had no idea this plan existed until a reader brought it to my attention. I haven't seen it advertised anywhere, and it's not prominently mentioned on AT&T's site; you have to drill into the Prepaid section to find it. As noted above, it's an online-only offer: If you stop by an AT&T store hoping to sign up, there's a good chance the sales folks won't even know about it.

Read more: Verizon vs AT&T vs T-Mobile vs Sprint: Choose the best 5G carrier

As you'd expect, the plan affords unlimited talk and texting -- not just in the US, but also in Canada and Mexico. (Mint Mobile, for its part, lets you make calls to those countries, but calling from within them costs extra.) It includes 8GB of 4G LTE data, and any unused data can roll over (though only for one month). You get a mobile hotspot as well, same as with Mint; it draws from your monthly data allotment.

The Canada/Mexico and rollover benefits give AT&T a slight edge over Mint Mobile, but the big appeal for some folks will be AT&T's network. Depending on where you live, it might be a better option than T-Mobile's, which is what Mint uses.

To take advantage of AT&T's deal, you'll need to either buy a phone or bring one that's compatible with the network. You'll pay $4.99 (plus tax) for a SIM card and $300 for the 12-month plan, bringing your out-the-door total to about $305. Although the "due monthly" amount is listed as $0.00, there may be additional taxes and fees. It's not immediately clear to me from the terms.

What do you think? Is this a sweet enough deal to convince you to choose AT&T over Mint Mobile? Or AT&T over AT&T, assuming you were paying monthly before?

Note: Originally published last year. Updated to reflect new sale prices and/or availability.

Read More: All the latest AT&T coupons

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