Watch out, line cutters. American Airlines is rolling out new technology across the country to crack down on travelers trying to get on the airplane before their boarding group is called.

Customers who try to scan a boarding pass before their group is called will hear a two-note sound and be turned away, the airline said.

American Airlines has nine boarding groups, ranging from first-class customers and top-tier frequent flyers to travelers who purchased basic economy fares, or the least-expensive tickets. Airlines reward their high-paying elite frequent flyers with perks such as earlier boarding, and have been trying to keep it exclusive.

The new technology as of Wednesday is in more than 100 nonhub airports around the U.S. following tests over the past month at Albuquerque International Sunport, Ronald Reagan Washington National Airport and Tucson International Airport, American Airlines said.

The airline plans to roll it out to hubs later.

The technology will roll out just as American expects 8.3 million people to board its planes between Nov. 21 and Dec. 3, which it considers the Thanksgiving travel period, an increase of 500,000 customers over last year.

Other airlines have experimented with new ways to prevent gate crowding, which helps board planes faster while also trying to protect early boarding for the swelling ranks of elite frequent flyer loyalty program members.

United Airlines texts customers when it is time to board and provides live updates to customer’s iPhones and Apple Watches with a countdown-to-boarding clock. It also has digital signs showing which boarding group has been called.