The outage affected major cities including New York, Houston, Philadelphia, Dallas and Miami, triggering 911 disruption warnings in some areas and prompting Verizon to offer affected customers a $20 account credit.

Verizon resolved a nationwide outage Wednesday that knocked out cellular voice and data services for millions of U.S. customers for more than 10 hours, the company confirmed.

Disruption reports began appearing around noon ET, according to the outage tracker Downdetector, which logged more than 1.5 million complaints before 5 p.m. Reports peaked in the early afternoon but remained elevated throughout the day. Verizon said service was fully restored by 10:20 p.m. ET. The New York-based carrier did not disclose what caused the failure.

“Today, we let many of our customers down and for that, we are truly sorry,” Verizon said in posts to social media. A company spokesperson later said affected customers would receive a $20 account credit through Verizon’s app, which on average “covers multiple days of service,” and that the company would directly contact its business customers with compensation.

Verizon previously said it had deployed engineering teams to address “an issue impacting wireless voice and data services.”

Affected areas and 911 concerns

Affected users reported phones displaying “SOS” mode or no-signal messages. In New York, alerts warned that the outage could disrupt 911 calls, urging residents to try landlines, devices from other carriers, or to visit a local police or fire station in the event of an emergency. Other major hubs affected included Houston, Philadelphia, Dallas and Miami, per Downdetector. Many customers across the country also reported disruptions.

A handful of outage reports for other carriers surfaced on Wednesday, but T-Mobile and AT&T both confirmed their services were operating normally. Both said their customers may have encountered difficulties reaching people on Verizon’s network.

Options when cellular service fails

When cellular outages occur, some carriers advise customers to connect to Wi-Fi and use internet calling. Newer iPhones also support messaging via satellite when Wi-Fi is unavailable.