AT&T Inc. (NYSE: T) is adding options to its wireless plans that will let users share a bucket of data across up to 10 devices, including smartphones and tablets.

The carrier has been talking about making this move for a while now and plans to launch the new "Mobile Share" plans at the end of August, just two months after Verizon Wireless introduced its "Share Everything" buckets. (See Verizon: One Data Bucket to Rule Them All.)

The optional plans include unlimited voice and text, and they must include at least one smartphone. On top of the basic per month charge that ranges from $40 for the 1GB plan to $200 for the 20GB plan, AT&T is charging US$45 per smartphone added to the bucket on its lowest (1GB) plan, but that additional charge decreases to $35 or $30 depending on which monthly plan the user has chosen.

After smartphones are added, AT&T charges an additional $30 per month for each basic and quick messaging phone added, $20 per laptop, laptop connect card and netbook added, and $10 per month for each additional tablet or gaming device. AT&T also charges $15 per additional gigabyte of data.

Verizon charges the same to add devices on its Share Everything plans, except that smartphone additions are always $40, meaning that AT&T's plans are more economical at 1GB, the same at 4GB, and Verizon wins at 6GB and 10GB:

Table 1: AT&T & Verizon's Data-Sharing Options

AT&T isn't requiring its customers to make the move to Mobile Share, nor is it charging a fee to do so. Verizon, on the other hand, is phasing out its old unlimited plans for the buckets. AT&T breaks down the new plans, here.

Why this matters
While not unexpected, the move to shared data is a big change for operators, albeit one that makes sense from the wireless providers' standpoint given the number of devices they're encouraging users to buy. The plans on both operators may lessen costs for some families and businesses, but they can make mobile data usage more expensive for individuals in certain cases. With increased access costs and tack-on charges for additional devices, customers may find themselves paying more for a data bucket than they did when their bills were separate.

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— Sarah Reedy, Senior Reporter, Light Reading Mobile