NORTH TEXAS (CBS 11 NEWS) – You’ve heard the sound for years on TV and radio – the warning tones, the Emergency Alert System announcements.

Wednesday the federal government will conduct its first ever national test of the system. At 1pm CST every television and radio station in America –broadcast, cable, and satellite– will carry the same EAS message simultaneously for the very first time.

“The Emergency Alert System has never been tested in this national way before,” explained Don Dobbs, KTVT and KTXA Director of Engineering and Operations.

The EAS system is a daisy-chain network that will be triggered by officials in Washington and relayed throughout America.

“You’ll see a message at the top of the screen,” described Dobbs, “and you’ll hear an audio message originating from Washington containing the message that ‘this is only a test.’”

Though scheduled for only 30 seconds, Dobbs said hangups in relays could mean individual stations might not get their message for as long as 15 minutes. That’s why they run tests.

Emergency communications experts meeting with the media in Arlington Tuesday afternoon, said they are bracing for unwanted 911 calls; unwanted, and unnecessary, they say.

“We really don’t want the uninformed public to bring down the 911 system with calls about the test,” said Patty Cross, the manager of training and education for the Denco 911 System in Denton County. “Because we don’t want to make history in a bizarre or really weird, wrong way. “

While officials believe it’s essential to test the national system, not everyone thinks it’s a good idea. Some conservative radio hosts say it’s unnecessary over-reach by the government. Among them, locally-based Glenn Beck, who said it wasn’t even used on September 11 when the media kept everyone informed.

A statement on Beck’s website said, “Even when we had planes crash into buildings in three different cities, we didn’t need it. We didn’t need the White House to activate this and seize control of all the airwaves to give official information,” and added, “There’s no need to seize the airwaves to give us information. We have the system already in place.”

Local Homeland Security officials believe otherwise, including Dallas County Judge Clay Jenkins.

“Don’t read anything into it,” he cautions, “this is just a matter of national preparedness; federal government is doing their due diligence to make sure the system runs properly.”

The acid test comes Wednesday at 1pm, local time.

Click here for more information about the test.