Getty Images/Scott Olson

By CNN's Logan Whiteside

Are you ready to upgrade to the latest smartphone? Not so fast.

AT&T customers now have to wait two years to be eligible for an upgrade. Previously, the wait time was 20 months. This will affect AT&T customers with contracts ending on or after March 2014.

The company is taking Verizon’s lead. The two carriers tend to mimic each other’s policies, and Verizon changed its upgrade eligibility policy to 24-months earlier this year.

AT&T says the new policy simply aligns phone upgrades with standard two-year wireless contracts, but consumer advocates are concerned about the move.

The Consumer Federation of America’s Mark Cooper calls the change “unjustified.” He says because AT&T and Verizon are the biggest carriers, they have less incentive to offer consumer-friendly policies.

“Its intention and effect is to diminish competition. That’s the only purpose at this stage of the game,” said Cooper.

Customers flock to major carriers to get the latest technology, and carriers often subsidize the cost of expensive smartphones.

According to the Pew Research Center, 56% of all Americans now use smartphones. For AT&T, about 72% of the company’s 107 million subscribers own smartphones.  With the change in policy, users will be stuck with their phones longer.

Both Verizon and AT&T point out customers are free to purchase a new phone whenever they choose at the sticker price. They’ll just have to wait a bit longer for a cheaper option.