Be careful, line cutters. American Airlines is rolling out recent technology across the country to crack down on travelers attempting to board planes before their boarding group known as.

Customers who attempt to scan a boarding pass before their group known as will hear a two-tone tone and be turned away, the airline said.

American Airlines has nine boarding groups, starting from first-class customers and first-class frequent flyers to travelers who’ve purchased one-way economy fares or the most affordable tickets. Airlines reward their high-paid elite frequent flyers with perks like early boarding and have tried to maintain them exclusive.

The recent technology is in use at greater than 100 non-hub airports within the U.S. as of Wednesday, following tests last 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 comes just as American expects 8.3 million people to board its planes between Nov. 21 and Dec. 3, the Thanksgiving travel period, a rise of 500,000 customers from last yr.

Other airlines have been experimenting with recent methods to stop gate overcrowding, helping to board planes more quickly while attempting to ensure early boarding for the growing variety of elite members of frequent flyer loyalty programs.

United Airlines Text customers when it's time to board and live updates on the client's iPhones and Apple Watches with a countdown clock to boarding. There are also digital signs showing which boarding group has been called.