Today’s test of the Wireless Emergency Alert and Emergency Alert System sent a message to cell phones, televisions and radios across the country.

But what if you didn’t get a text message or alert on your cell phone? According to the Federal Emergency Management Agency, there could be several reasons.

The WEA alert started at 2:20 p.m. ET (1:20 p.m. CT) and lasted for about 30 minutes. Cell phone users received a message that said “THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed.”

If you didn’t receive a message, here are some possible reasons:

• You don’t have a WEA-compatible mobile device. While almost all carriers are part of the WEA system, it’s possible that some older phones don’t receive the alerts. You can see a list of WEA providers here.
• Your device wasn’t turned on
• Your device was in airplane mode
• You were on a phone call. According to FEMA, the national test will not interrupt a phone call.
• Your device wasn’t in the coverage area of a cell phone tower or you weren’t able to receive a signal from that tower
• Your device was in a geographic area where the wireless provider didn’t participate in WEA
• Some older phones that are capable of getting an alert will not display the message if the user is on a call or using data at that time.

What about prepaid phones?

According to FEMA, customers on prepaid should receive the message as long as their provider participates in WEA. The customers should receive the alerts just as customers with a traditional monthly service plan.

What are the different types of WEA messages?

Today’s alerts were a test of a system that is used fairly often. The most prominent way is through AMBER alerts that are issued by law enforcement as part of a search for an abducted child.

Imminent threat alerts also use WEA. They are issued by public safety officials during severe man-made or natural disasters where an imminent threat to life or property exists, such as tornadoes or dangerous flooding. They sometimes include “shelter in place” warnings.

National alerts are those issued by the federal government and are only used in the event of national emergencies.