U.S. carrier AT&T, the nation’s leading telco by subscribers, today shed more light on its upcoming shared data plans available to new and existing subscribers later this month. The new plans are designed to help folks share their cellular data across up to ten smartphones, tablets and other devices while enjoying unlimited voice minutes and text messages domestically. First hinted at in mid-July, the new plans will be officially put into effect on Thursday, August 23…

AT&T announced the new Mobile Share plans in a blog post.

Current customers, including business users, are not required to switch to the new plans. Should they decide to switch at some point, they can do so without a contract extension. All Mobile Share plans include mobile hotspot and tethering and provide free access to over 30,000 AT&T WiFi hotspots in the United States.

Shared data starts at $45 a month per smartphone plus an additional $40 for 1GB of data. You can choose your data allotment in 1/4/6/10/15/20GB tiers costing $40/$70/$90/$120/$160/$200. Adding a tablet to your plan will set you back an additional $10, or $20 in the case of a computer. Another smartphone with unlimited voice minutes and text messages will run your an additional $30 a month.

Here’s what the price matrix looks like.

Here’s your promo clip.

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More information is available on AT&T’s website here.

Important caveat: you cannot pick a shared data plan for your iPad or a Mac only because AT&T mandates that at least one of the devices be a smartphone.

It’s nice that AT&T has kept existing plans so people are not being forced into Mobile Share plans, unlike Verizon which in late-June imposed new shared data plans on everyone.

What do you guys think?