A cyberattack was responsible for the week-long outage affecting Cellcom wireless network
May 21, 2025
Cellcom, a regional wireless carrier based in Wisconsin (US), announced that a cyberattack is the cause of a service outage it faced during the past week.
Cellcom, a regional wireless carrier in Wisconsin, confirmed a cyberattack that caused a week-long outage affecting voice and text services in Wisconsin and Upper Michigan. The company announced it has begun restoring services and stated it had protocols in place for such incidents.
The carrier stated the cyberattack affected a network area that is not linked to the storage of sensitive information, and there’s no evidence that customer personal or financial information was compromised.
“We experienced a cyber incident. While this is unfortunate, it’s not something we were unprepared for. We have protocols and plans in place for exactly this kind of situation. From the start, we’ve followed those plans — including engaging outside cybersecurity experts, notifying the FBI and Wisconsin officials, and working around the clock to bring systems safely back online.” reads the letter sent to the customers. “The incident was concentrated on an area of our network separate from where we store sensitive information related to you, our Cellcom/ Nsight family. We have no evidence that personal information related to you, your name, your addresses, your financial information, is impacted by this event.”
The company notified local authorities and is mitigating the incident with the help of external cybersecurity experts.
Cellcom expects to fully restore its services by the end of this week.
“While we would like to provide a timeline for full restoration, we are unable to share exact milestones with complete confidence. Our team continues to build on the progress shared yesterday and our best estimate is that full service will be restored by or before the end of this week.” states the company.
The company did not provide details about the attack; however, the outage suggests that Cellcom was the victim of a ransomware attack. As of now, no ransomware group has claimed responsibility.
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