11:40 AM EDT, 07/12/2024 (MT Newswires) -- AT&T ( T ) said Friday that hackers accessed records of calls and texts spanning roughly six months, affecting "nearly all" of its cellular customers and clients of wireless providers that use its network.

The telecom company said an attacker is believed to have accessed an AT&T ( T ) workspace on a third-party cloud platform, stealing customer call and text data from May 1, 2022, to Oct. 31, 2022, as well as on Jan. 2, 2023, according to a regulatory filing. The company became aware of the incident on April 19.

Compromised data include telephone numbers, the number of interactions and aggregate call duration for a day or month. Some records also include one or more cell site identification numbers. However, the data does not contain the content of calls or texts, or other "personally identifiable information" like social security numbers and dates of birth, the company said. AT&T ( T ) plans to notify all impacted customers.

AT&T ( T ) said it doesn't believe the compromised data is publicly available. The company said it has taken additional measures in response to the attack, including "closing off the point of unlawful access."

The US Department of Justice determined on May 9, 2024, and June 5, 2024, that "a delay in providing public disclosure was warranted," the company said in the filing.

Law enforcement agencies are working to arrest those involved in the incident, with "at least one person" arrested, according to AT&T ( T ).

"As of the date of this filing, this incident has not had a material impact on AT&T's ( T ) operations, and AT&T ( T ) does not believe that this incident is reasonably likely to materially impact AT&T's ( T ) financial condition or results of operations," the company said.

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