INDIANAPOLIS (AP) — Indiana will be one of 24 states, territories and districts participating in the largest-to-date test of the Emergency Alert System.

The Indiana Department of Homeland Security says test is due to be held Wednesday at 2:20 p.m. EST and 1:20 p.m. CST.

The test is voluntary for broadcasters and will be similar to the monthly emergency alert tests that the public sees on a regular basis. It is expected to last about one minute and will verify the delivery and broadcast of a national test message and assess the readiness for distribution of a national-level test message.

The test message which appears on television and sounds on radio is nearly identical to the regular monthly test messages of the Emergency Alert System.