Cell Phone Outage History: 6 of 11 Major Outages Began With a Network Change, and Hurricane Maria Cut 95% of Puerto Rico’s Cell Sites

This is the record of US cell phone outages the FCC has documented since 2014, rebuilt from the agency’s own outage reports, 911 enforcement orders and 466 disaster status reports. Of the 11 carrier outages with a published cause, 6 began with a configuration, software or maintenance change. The largest, AT&T on February 22, 2024, blocked more than 92 million calls. In disasters, power failures take down the most cell sites.

Timeline of major US cell phone outages

The FCC learns of large outages through its Network Outage Reporting System (NORS). A wireless outage must be reported when it lasts at least 30 minutes and potentially affects at least 900,000 user minutes or a 911 call center, but the FCC treats those filings as presumed confidential, so no public outage database exists. What the public record does contain is the outages the FCC chose to investigate in published reports, consent decrees and notices. These are the 12 wireless events in those documents, sized by duration.

Circle size grows with the logarithm of duration (Cellcom’s 13-day outage is the largest). Durations for 911-only events cover the 911 failure, not general service. Hover a circle for details.

n/s: not stated in the FCC document. Cellcom’s duration and cause are the company’s statements as quoted in the FCC notice. Verizon’s January 2026 outage remains under investigation in PS Docket 26-21.

Two outages stand apart. AT&T’s 2024 failure began three minutes after an employee put a misconfigured network element into production at 2:42 AM Central time; rolling back the change took close to two hours, but full restoration took at least 12 hours because AT&T’s device registration systems were overwhelmed by re-registration requests. T-Mobile’s 2020 outage began with a failed fiber link in the Southeast at 12:33 PM Eastern and lasted until 12:46 AM, because a misconfigured router and a latent software flaw spread a registration storm nationwide. AT&T alone reported 30,410,776 of its own mobile calls blocked from reaching T-Mobile customers that day.

What causes cell phone outages: changes, not storms

Sorting the 11 events by the root cause the FCC (or, for Cellcom, the company) described: 6 started with a change the carrier or its contractor made (a software upgrade, a configuration push, a reapplied security file, an untracked test), 2 with an equipment failure, 2 with a fiber or third-party network failure, and 1 with a cyber incident. The FCC drew the same conclusion in November 2024, writing that recent outage data shows that changes to operational networks, including software updates and configuration changes, require careful preparation and planning. Verizon’s December 2022 outage is the starkest example: the file that caused it was already known to be flawed from an October 2022 outage.

Cell sites knocked out by disasters

During hurricanes, wildfires and other disasters, the FCC activates its Disaster Information Reporting System (DIRS) and publishes a daily Communications Status Report with the number and share of cell sites out of service in each county. We downloaded all 466 of those reports listed in the FCC’s document index, from August 2017 to October 2026, and parsed the county tables in 451 of them, covering 44 events. Each bar is the worst day for the share of cell sites out, among reports covering at least half of the event’s largest reporting area. Readers tracking which states draw the most federal disaster aid can compare this with disaster declarations by state.

Events whose peak report covered at least 100 cell sites. Red: 50% or more; blue: 20% to 50%. A cell site outage does not always mean no service, because neighbouring sites overlap; the FCC makes the same caveat in every report.

Hurricane Maria is in a class of its own: on September 21, 2017, 1,703 of 1,789 cell sites in Puerto Rico (95.2%) were out, and the FCC kept publishing Maria reports until March 21, 2018. Pacific typhoons come next: Typhoon Mawar (Guam, 2023), Sinlaku (2026) and Bavi (2026) each knocked out more than 40% of sites at their peak, and on each one’s worst day at least 90% of the cause counts were power. 10 events in all passed 25%. Hurricane Helene’s percentage looks modest because its reporting area covered 50,800 sites in six states, but at its worst it had 5,855 cell sites down, the most of any event. In Buncombe County, North Carolina (Asheville), 285 of 348 sites were out on September 28, 2024. The smallest areas can be the most extreme: on August 12, 2023, all 21 cell sites serving Lahaina and five neighbouring West Maui communities were out after the wildfire.

Power, not wind, takes most cell sites down

Since July 2019 the reports split outages into damage, transport (the fiber or microwave link behind the site) and power. On the worst day of each of the 34 events with that breakdown, power accounted for 70% of the cause counts, transport for 24% and physical damage for only 6%. Power was the largest cause in 24 of the 34. On Helene’s worst day (Sep 28, 2024), 4,385 sites were out for power, 1,264 for transport and 47 for damage. For how often the grid itself fails, state by state, see our power outage statistics.

The 14 events with the most cell sites out on their worst day, among events whose reports include cause columns. Shares are of the three cause counts; a site can have more than one cause.

Peak share uses reports covering at least half of the event’s largest reporting area, so a late report on a few remaining counties cannot set the peak. Worst state or territory requires at least 50 sites. The 2023 Hawaii wildfire reports give no county table and are described in the text.

Verizon, AT&T and T-Mobile outage history

911 outage penalties over time

Every penalty in this record was imposed under the 911 rules (failing to deliver 911 calls) or the outage notification rules (failing to warn 911 call centers or the FCC), not for the outage itself. The 19 settlements below total $90.1M; $47.4M of that came from orders involving wireless carriers. The largest single payments are T-Mobile’s $19.5M (2021) and $17.5M (2015), and Charter’s $15M (2024) for a VoIP outage. The most recent order in the FCC’s document index is from August 26, 2024; we found none in the 26 months since.

Settlement totals exclude the 2023 Lumen proposed forfeiture (a Notice of Apparent Liability, not a payment). “Partly” means the order covered an AT&T wireless outage together with wireline or VoIP services.

What this means for MSPs

• Put a different carrier on the backup path. A cellular failover link on an SD-WAN edge does nothing if it rides the same carrier as the outage. In AT&T’s 2024 outage, phones that fell back to SOS mode on another carrier’s network could still reach 911, while those on AT&T’s network could not. Match the failover SIM to a different network than the client’s primary mobile and broadband providers, and test it quarterly.
• Do not treat Wi-Fi calling as an independent backup. Wi-Fi calling still needs the carrier’s core network to register the phone. T-Mobile’s 2020 outage broke Wi-Fi calling along with cellular, and AT&T customers reported 502 errors turning it on in 2024. For a client’s critical lines, a separate VoIP or UCaaS path is the real fallback.
• Plan for SMS and voice MFA failing. One commenter in the 2020 T-Mobile record could not log in to work because his employer’s two-factor codes arrived by phone. Make authenticator apps or hardware keys the default, with break-glass accounts that do not depend on a mobile network.
• Size backup power for days, not hours. Power causes most disaster cell-site outages, and the client’s own router, switch and cellular gateway need power too. For sites in hurricane and typhoon zones, check UPS runtime against the multi-day outages in the DIRS data above, and consider satellite as a second path; our Starlink statistics cover coverage and capacity.
• Know where to check status. During declared disasters, the FCC publishes a daily Communications Status Report with cell sites out by county. For sunny-day outages, the carriers’ own newsrooms and status pages are the primary source; third-party outage trackers count user reports, not failures.
• Write cellular into the SLA. Carrier credits are small (Verizon offered $20 after its 2026 outage; some T-Mobile customers got $5 or $10 in 2020). Exclude carrier-wide outages from your response-time commitments unless you sell diverse failover, and price that failover against the cost of downtime for the client.

Frequently asked questions

What was the biggest cell phone outage in US history?

Among the outages the FCC has documented, AT&T’s outage of February 22, 2024: all voice and 5G data service was down for at least 12 hours, affecting more than 125 million devices, blocking more than 92 million calls and more than 25,000 calls to 911. T-Mobile’s June 15, 2020 outage lasted 12 hours 13 minutes, with at least 41% of calls failing.

Has Verizon had a nationwide outage?

Yes. On January 14, 2026, Verizon had an outage the FCC says lasted at least ten hours and affected millions of customers. Verizon said it was resolved at 10:15 PM ET and offered a $20 account credit. The FCC opened PS Docket 26-21 to investigate.

What causes cell phone outages?

In the FCC-documented sunny-day outages we compiled, 6 of the 11 with a stated cause began with a configuration, software or maintenance change by the carrier or its contractor. In disasters, loss of power is the main cause: across 34 events with cause data, power accounted for 70% of cell sites out on each event’s worst day.

What percentage of cell towers go down in a hurricane?

It varies widely. In FCC DIRS reports, Hurricane Maria left 95.2% of Puerto Rico’s cell sites out on September 21, 2017. Hurricane Helene peaked at 11.5% of the reporting area but knocked out 5,855 sites at its worst, the most of any event. Across all 44 DIRS events since 2017, the median peak was 8.1%.

Do carriers get fined for cell phone outages?

Not for the outage itself. Penalties come from the 911 and outage notification rules. The FCC has collected $90.1M in the 19 911-outage settlements listed here (2015 to 2024), $47.4M of it in settlements involving wireless carriers. T-Mobile paid $37M, AT&T $6.66M and Verizon $4.72M. The latest order we found is dated August 26, 2024; AT&T’s February 2024 outage was referred to enforcement with no public outcome yet.

Does Wi-Fi calling work during a cell phone outage?

Not always. In the 2020 T-Mobile outage, Wi-Fi calling failed too because phones could not register with the carrier’s core network. During AT&T’s 2024 outage, AT&T told customers to use Wi-Fi calling, but some users reportedly got a 502 Bad Gateway error when turning it on.

Methodology

References

1. FCC PSHSB, February 22, 2024 AT&T Mobility Network Outage Report and Findings (July 22, 2024). Accessed October 2026.
2. FCC PSHSB, June 15, 2020 T-Mobile Network Outage Report (October 22, 2020). Accessed October 2026.
3. FCC PSHSB, Final Report on March 8, 2017 AT&T Mobility VoLTE 911 Outage. Accessed October 2026.
4. FCC PSHSB, Incident Report: April 27, 2021 Verizon Wireless Outage. Accessed October 2026.
5. FCC PSHSB, Public Notice DA 26-94 on the January 2026 Verizon outage. Accessed October 2026.
6. FCC PSHSB, Public Notice DA 25-607 on the May 2025 Cellcom outage. Accessed October 2026.
7. FCC PSHSB, Public Notice DA 24-1166 on network reliability best practices. Accessed October 2026.
8. FCC PSHSB, Public Notice DA 26-1033 on 911 and 988 outage notification obligations. Accessed October 2026.
9. FCC PSHSB, December 27, 2018 CenturyLink Network Outage Report. Accessed October 2026.
10. FCC Enforcement Bureau orders and consent decrees: DA-15-308, DA-15-406, DA-15-421, DA-15-808, DA-16-735, DA-18-649, DA-19-1061, DA-19-1063, DA-20-1469, DA-21-1439, DA-21-1503, DA-21-1542, DA-21-1543, DA-21-1541, DA-23-337, DA-23-613, FCC-23-81, DA-24-578, DA-24-708, DA-24-842. Accessed October 2026.
11. FCC, Disaster Information Reporting System, and the 466 Communications Status Reports listed in the CSV download (for example Hurricane Maria, Sep 21, 2017 and Hurricane Helene, Sep 28, 2024). Accessed October 2026.
12. FCC website content API (document index). Accessed October 2026.
13. Verizon, An update on our network outage (January 14 to 15, 2026). Accessed October 2026.