The new AT&T Mobile Share plans include unlimited calling and messaging and let customers combine as many as 10 devices under one monthly data allotment. Verizon started a similar plan starting at $90 last month.

AT&T and Verizon Wireless are pushing a shared-plan approach to encourage customers to use more devices and ultimately buy bigger packages of data. By bundling services onto one bill carriers are trying to stop erosion of calling and messaging revenue as consumers who call less and use free messaging services migrate to cheaper packages.

“These aren’t entry-level price plans,” said Roger Entner with Recon Analytics of Dedham, Massachusetts. “These are forward-looking plans for people with multiple devices — the heavy data users of today, who will be more common down the road,” he said.

The plan starts with $40 for 1 gigabyte of data and $45 per smartphone, Dallas-based AT&T said in a statement. The next tier is $70 for 4 gigabytes of data and $40 per smartphone, 6 gigabytes costs $90 and each smartphone is $35, 10 gigabytes is $120 with $30 per smartphone, 15 gigabytes is $160 with a $30 smartphone charge and the maximum is a 20 gigabytes for $200. Users can add phones that only make calls and texts for $30 a month, laptops for $20 a month and tablets for $10 a month.

More Choices

The idea is to offer consumers more choice, said David Christopher, chief marketing officer for AT&T Mobility. “The future is all about connecting mobile devices to the Internet and we’re making it easier to do that,” Christopher said in a telephone interview.

AT&T says isn’t discontinuing its existing individual and family plans.

The shared-data offering also includes mobile hotspot and tethering features that allow devices to share their data connections.

AT&T gained less than 1 percent to $35.93 at 10:36 a.m. in New York. Through yesterday, the shares have risen 18 percent this year. Verizon Communications Inc., which jointly owns Verizon Wireless with Vodafone Group Plc, rose 0.2 percent to $45.73.