CNET

T-Mobile is offering more data to customers willing to sign up for a new family plan, but it's also eliminating one option for unlimited data.

The nation's fourth-largest wireless carrier on Tuesday unveiled a new family plan that gives each member 10 gigabytes of data. A two-person plan costs $100, while each additional line costs $20. The plan will be available Wednesday.

The $100, two-person plan, however, displaces an existing option that offered unlimited high-speed data at the same price.

The move is just the latest in broader push by T-Mobile to pressure its rivals in the wireless business with a series of incentives and features to entice new customers and retain existing ones. The moves come at a time when all the wireless carriers have stepped up the competition with new plan options and renewed marketing pushes.

It comes on the heels of last week's announcement by T-Mobile that customers would be able to use their smartphones in Mexico or Canada without any additional charges. And last month, the company introduced a combination leasing and installment plan that allows customers to upgrade their smartphone up to three times a year.

T-Mobile CEO John Legere kicked things off Tuesday with a series of tweets knocking Verizon Wireless' family plan. His criticism: The 10-gigabyte family plan that Verizon offers costs $140 a month between the service plan and device access fees. He then tweeted a link to his new plan.

"Why share Verizon's 10 GB with everyone when you can have 10 GB of America's fastest 4G LTE all to yourself?" Legere said in a statement.

Verizon, for its part, believes consumers prefer shared data plans.

"Great plans always start with a great network, and our plans match the way customers use wireless service," said a Verizon spokeswoman. "Sharing, not only among family members but across devices, is the way wireless works today."

Family time

The new family plan has a promotional element -- any family getting three lines can add a fourth line at no cost, for a total bill of $120 for four people, each getting 10 GB of data. Customers have to sign up by Labor Day, and there isn't an expiration date. While the program has no end date, the free fourth line goes away after September 7.

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The $20 monthly fee to add a line is double the cost of its previous family plan. But in return, each member gets far more data than before. Customers typically get 1GB of data under than plan, but a promotion last year gave customers 2.5GB. As with the previous family plan, up to 10 members can sign up. There is no way to juggle a $10 fee for less data -- every member must sign up for the 10GB. While that's a boon to families that use a lot of data, it may give pause to those whose members seldom use their smartphones.

T-Mobile is making its push for the family plan ahead of the critical back-to-school season, according to Chief Marketing Officer Andrew Sherrard. He noted the company saw a lot of success with its promotional family plan from a year ago.

"It's one of the biggest times of the year as families think about resetting their plans," he said in an interview.

Chief Operating Officer Mike Sievert hinted at the new plan in an interview last week. T-Mobile said the Mexico-Canada benefit would only apply to customers who sign up for a new plan available on Wednesday, seemingly leaving many customers already on existing promotional plans, like the four-person, 10GB family plan, out of luck. Tuesday's new plan is designed for those customers looking to switch and be eligible to use their smartphones in Mexico or Canada without roaming charges.

For T-Mobile customers who want to stick on their existing plans, including an older unlimited data offering, there's the option to pay $10 a month to access the company's "Mobile Without Borders" plan.

Curtailing of unlimited

T-Mobile is just the latest carrier to tweak its unlimited-data offering. The elimination of its two-person, $100 unlimited data plan means individuals either sign up for their own $80 unlimited data plan, or add an unlimited data line to a family plan for $40 a month.

The moves comes after Sprint eliminated its $50 unlimited data plan for iPhone users, instead upping it to $60 a month.

While T-Mobile and Sprint both offer unlimited data as an option -- larger rivals AT&T and Verizon Wireless eliminated their plans years ago -- they have eased off on their commitments to keeping it around. Sprint CEO Marcelo Claure has hinted at price increases, and said he would continue to look at it to ensure it makes financial sense.

T-Mobile has committed to offering unlimited data for two years, and hasn't said what would happen once it hits that point.

"We can't commit to it forever," Sherrard said.

Updated at 8:52 a.m. PT: To include comment from a T-Mobile executive and Verizon spokeswoman.