An emergency alert system test will be sent this afternoon to almost everyone in Ontario with a cell phone. The test will happen for everyone at the exact same time, with an audio tone that sounds similar to an ambulance.

It might be jarring, but don't be alarmed — it's only a test. 

The CRTC and Alert Ready, Canada's national emergency alert system, have confirmed that all wireless devices connected to an LTE network in Toronto will receive visual and audio notifications on Monday afternoon as a part of regular testing.

REMINDER: TODAY at 1:55pm, #Ontario will be testing #emergency alerts on compatible mobile devices, TV and radio using the #AlertReady system. This is a test only. Check your phone's compatibility: https://t.co/RHAwoLFEfC
#ONready #EPWeek2018 pic.twitter.com/A9pAgLVa1y

— Ontario Warnings (@OntarioWarnings) May 7, 2018

This will mark the first time that emergency alerts have gone out to mobile phone users directly, in addition to those sent through TV and radio networks.

People in Ontario can expect to get the notifications at 1:55 p.m. today, according to the Alert Ready website, with the rest of the country (save for Quebec and Nunavut) to follow in coming days.

The City of Toronto's Office of Emergency Management issued a press release on Monday morning to remind residents about the test, which it says will "send emergency alerts to cell phones and wireless devices that are compatible with Wireless Public Alerting (WPA)."

NOTICE
🚨 PUBLIC ALERTING TESTS on compatible LTE-connected #wireless devices, television and radio.

Dates:
May 7: Ontario and Quebec.
May 9: Y.T, B.C, Alta., N.W.T., Sask., Man., N.B, N.S, P-E-I, N.L. https://t.co/XfXVpYoCkT pic.twitter.com/i3UoXkx6bF

— CRTCeng (@CRTCeng) May 3, 2018

Users will hear a tone similar to an ambulance alarm or feel an 8-second-long vibration at the time of the alert, according to the Canadian Press.

If your phone is turned off, nothing will happen. If you're using it to speak with someone, however, a sound "similar to a call waiting tone" will interrupt your conversation.

Fortunately, these tests will only take place once per year (unlike TV and radio emergency alert tests, which happen up to five times every 12 months.) They're also completely free, so don't fret about additional charges.