In a Friday advisory, FEMA noted that by using the Wireless Emergency Alert (WEA) system, anyone with US-based cell service will receive the president's message in the event of a national emergency.
That's everyone with a US-based phone and no, text messages using this protocol cannot be blocked.
On Thursday, FEMA will test the WEA system with the following message, "THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed." A similar Emergency Alert System (EAS) message will be broadcast over television, radio and cable-based video networks minutes after the text message is sent, TechCrunch reported Saturday.
Emergency alerts have long been used to tell US citizens subscribing to the opt-in service about severe weather events or missing children. However, presidential alerts have not been tested before, leading many to wonder if Trump will make use of the network with the same rantings popularized in his tweets.
Earlier this year, it took Hawaii authorities at least 38 minutes to retract an emergency telephone text notice of an inbound ballistic missile that ended with the words, "this is not a drill," prompting mass panic.
Hawaii is well within the range of ballistic missiles developed by North Korea, which has previously threatened to arm ICBMs with nuclear warheads to attack the United States.
Following the incident, the Hawaii Emergency Management Administrator, Maj. Gen. Vern Miyagi, stepped down after taking full responsibility for the false ballistic missile alert incident.