While many cellphones were buzzing with test alerts from the president of the United States, others sat in silence.
Several people used Twitter and other social media to note they failed to receive the test presidential alert sent by FEMA on Wednesday at 2:18 p.m. ET.
"I did not get an Alert System text today," wrote one Twitter user.
The warning system was originally put in place under former President George W. Bush for radio and TV and then later updated during the tenure of former President Barack Obama to include cellphones. It wasn't until Wednesday that it got its first test.
Alerts go out in the event of a national emergency, and unlike local weather or Amber alerts, users don't have the option to disable them.
In a statement, FEMA said cellphones compatible with the Wireless Emergency Alerts system that are turned on and within range of an active cell tower were capable of getting the message.
"Additionally, if a user is on a call, or with an active data session open on their phone, they might not have received the message," FEMA said.
FEMA is encouraging the public to send comments on the test to FEMA-National-Test@fema.dhs.gov. Among the details people who did not get the alert should send: What device they use, their wireless provider, whether they were using their phone when the alert went out, and whether others nearby received the alert.