Verizon Wireless agreed to pay a penalty of just over $1 million and implement an internal compliance plan to resolve a Federal Communications Commission (FCC) investigation into an emergency call outage across six US states in December 2022.

In a statement, the regulator explained the operator’s VoLTE service had been impacted by an outage on 21 December 2022 lasting for an hour and three quarters. During that time, it noted, hundreds of calls to the 911 emergency services line had failed to connect.

Areas hit were Alabama, Florida, Georgia, North Carolina, South Carolina and Tennessee.

The FCC noted the outage had been similar to one suffered by the company’s users two months earlier with Verizon said to have taken “action to protect against further, similar” problems in the aftermath of the one in October.

In the consent decree outlining the civil penalty and terminating the investigation, the cause of the December issue was pinned to the reapplication of a flawed security update file by an employee.

It noted “due to insufficient naming convention protocols” and a failure to follow current implementation procedure “the flawed security policy update file was reintroduced into the Verizon Wireless network”.

The operator was blamed for not removing the problem file from available security policies even though it was known to have been related to the issue earlier in the year.

As part of the agreement reached between the operator and FCC, Verizon will implement a “robust compliance plan” including risk assessments related to emergency calls and introducing enhanced processes for security policy updates.