AT&T said it will provide a $5 credit to customers who were "potentially impacted" by Thursday's widespread network outage, when tens of thousands of customers reported losing cellphone service for much of the day.

In a letter sent Sunday to AT&T employees, CEO John Stankey said the $5 credit is the cost of "essentially a full day of service."

The carrier apologized to customers for the disruption, which the company said was "due to the application and execution of an incorrect process used while working to expand our network, not a cyber attack."

The outage also created problems for people with service from rival carriers, as many were unable to reach people who use the AT&T network. Additionally, the issue snarled 911 service, with some municipalities saying residents with AT&T service were having problems reaching the number, while others warned residents not to call 911 simply to test whether their phones worked.

"We understand [the outage] may have impacted their ability to connect with family, friends, and others," AT&T said in its statement. "To help make it right, we're reaching out to potentially impacted customers and we're proactively applying a credit to their accounts."

Here's what to know.

How much is the AT&T outage credit?

AT&T is offering $5 per account for customers who may have been affected by the telecom's February 22 network outage. 

Who qualifies for the outage credit?

Individuals and some small businesses who were impacted by the outage qualify for the $5 credit. 

However, AT&T said AT&T Business, AT&T Prepaid and Cricket customers are ineligible for the credit.

Why aren't AT&T Business, Prepaid or Cricket customers eligible for the credit?

AT&T said it is "working closely" with its AT&T Business customers to address their concerns, but didn't specify whether those accounts will receive a refund.

"Prepaid customers will have options available to them if they were impacted," said Stankey in his letter to employees. He didn't disclose what options AT&T will offer those customers.

The company also didn't specify why Cricket customers aren't eligible for the $5 credit. AT&T didn't immediately respond to a request for comment.

How do I get the $5 credit?

AT&T said it will automatically apply the $5 credit to your account, with the credit appearing within two billing cycles.

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