It is a little after 10 on Thursday morning, and Outlook is stuck on “Trying to connect.” You flip over to Teams to ask whether anyone else is seeing it, and your message just sits there. So you pick up the desk phone to call your manager and get nothing, because the phones run through Teams too. Somewhere on the other end, a customer is calling your main number and getting the same nothing.
Key takeaways
- On November 12, 2026, a Microsoft 365 outage disrupted Outlook, Teams, SharePoint, and Copilot for hours, after a separate Teams incident earlier that morning.
- When email, chat, meetings, files, and phones all run through one platform, a single outage can reach every one of them at the same time.
- Diversifying does not mean leaving Microsoft. It means running calling on a separate platform that works with Teams, so one side keeps working when the other does not.
What happened to Microsoft 365 on November 12?
A Microsoft 365 outage on Thursday, November 12, 2026 disrupted Outlook, Teams, SharePoint, and Copilot for users in many regions. The day began with a separate Teams incident in North America that Microsoft resolved within about 90 minutes. The larger outage started soon after and was still listed as a service degradation that afternoon.
Here is the timeline, in Pacific time:
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7:40 a.m. Microsoft said it was investigating users having trouble accessing or using Teams in North America, tracked as incident TM1550488, according to Technobezz.
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9:09 a.m. Microsoft said its fix had restored service and that customer impact was fully resolved, Technobezz reported.
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9:39 a.m. User reports for a second, larger problem began climbing, according to Techaeris.
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9:54 a.m. Microsoft made its first post on X about users having trouble reaching Exchange Online mailboxes, WebProNews reported.
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10:07 a.m. Microsoft confirmed the issue could affect Microsoft 365 connectivity for users in any region, USA TODAY reported.
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10:09 a.m. Outlook reports on Downdetector peaked at 128,874, according to USA TODAY.
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10:26 a.m. Microsoft opened advisory MO1550821. BleepingComputer reported that it listed Exchange Online, Teams, SharePoint Online, Microsoft 365 Copilot, and Defender XDR as services customers might not be able to reach.
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About 1:50 p.m. Outlook reports had fallen to about 49,000, USA TODAY reported.
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2:11 p.m. Microsoft's service health page still listed the incident as a service degradation, according to Technobezz.
Microsoft first pointed to heavy load on part of its infrastructure. It then said on X that the load came from "a number of servers being unexpectedly unavailable," which strained the servers that were left. Later updates said servers were failing automated health checks, that Microsoft had paused all deployments, and that it was bringing servers back with a different health check method.
Microsoft had not named a root cause in the updates available that afternoon. Techaeris noted that Microsoft has not attributed the outage to a cyberattack, and IBTimes UK reported that Microsoft had not said whether the morning Teams incident was connected to the larger outage.
The effects reached well beyond office inboxes. KPRC Click2Houston reported that Sugar Land, Pearland, and League City, Texas, said the outage was affecting city services.
This was also not the first long outage of the year. A Microsoft 365 outage that began on August 31 ran for days and affected Outlook, SharePoint, Copilot, Teams, and other services. Microsoft's status page attributed it to a core authentication configuration used by multiple Microsoft 365 services, TechCrunch reported.
Why does one Microsoft outage reach so much at once?
One outage reaches so much because so many jobs run on the same platform. Microsoft 365 handles email, chat, meetings, files, and, for many organizations, phone calls. When a shared part of that platform has a problem, every service that depends on it can feel it together, and staff have nothing left to fall back on.
That is a different question from which provider is more reliable. Every provider has incidents, and uptime promises do not settle it. Microsoft has backed Teams Phone, the add-on that turns Teams into a business phone system, with a 99.999% uptime commitment since April 2024, No Jitter reported. Large cloud phone providers advertise the same number, including RingCentral and Zoom, which offers up to 99.999%.
What differs is how much goes down together. If phones run on a separate platform and that platform has a bad day, email, chat, and meetings are still there to work around it. If Microsoft has a bad day, the phones keep ringing. November 12 was harder on organizations that had every one of those jobs in the same place.
What does it mean to diversify your business communications?
Diversifying means not running every communication job through one platform. For most organizations the simplest version is to keep Microsoft for email, chat, and meetings, and run phone calls on a separate platform that works with Teams. Staff keep the tools they know, and one outage no longer reaches everything.
How exposed you are today depends on which of three common setups you have
|
Your setup |
What a Microsoft outage can mean |
What to have in place |
|---|---|---|
|
Teams is the phone system. Numbers come from Microsoft or from a carrier connected to Teams (Microsoft's connection options). |
Calls are answered in the Teams client, so phones can be affected along with email, chat, and meetings. |
Ask your carrier what it can reroute when Teams is unreachable. For Direct Routing, Microsoft documents a Survivable Branch Appliance that keeps calls going when a site cannot reach Microsoft's cloud. |
|
A cloud phone provider's calling app runs inside Teams (this kind of service is often called UCaaS, short for Unified Communications as a Service), and calling runs on the provider's platform (how embedded apps work). |
It depends on the provider. Many handle the call outside Teams, so calling keeps running while staff lose their usual window. Some bridge calls through Teams itself, so ask how yours works. |
The provider's own desktop and mobile apps, or desk phones, installed and tested. |
|
The phone system is fully separate from Teams. |
Calls keep working. Chat and meetings may not. |
An agreed second way for staff to message each other. |
Here is the part most people miss. Putting your phone provider inside Teams does not mean Teams runs your phones. It means your team gets one familiar window while the calls travel on a completely separate platform. Teams can have the worst day of its year and your main line will still ring. Staff switch to the provider’s own app, on any computer or on their mobile, and get on with the day.
The City of Oceanside took this route when it moved its phones to the cloud. IT Director David Riha wanted communications that were easier to manage and integrated with Microsoft Teams. According to the city’s case study, the Teams integration meant employees did not have to learn a brand-new system, and adoption was smooth.
What can you do if everything runs through Microsoft today?
You do not have to rip anything out. The usual move is to keep Teams exactly where it is and shift the calling behind it to a separate phone platform. Staff still dial from the Teams window they already know. The difference only shows on a day like November 12, when the phones keep working anyway.
Picture that day with the calling on its own platform. Teams stalls mid-morning. Someone at the front desk opens the phone provider’s app on a laptop, or simply picks up the desk phone, and answers the next call. Nobody outside the building can tell anything is wrong. And if the phone provider ever has a bad day of its own, Teams, email, and meetings are still there to work around it.
Getting there starts with three questions:
- What do our phones depend on right now? If calls are answered in Teams and nowhere else, then a Teams problem is a phone problem. That is the gap to close.
- Can we keep Teams and our phone numbers? Staying in Teams is the whole idea. Several cloud phone providers can embed their dialer directly in the Teams app, TechTarget reports. Ask each provider how your existing numbers would move over.
- What would the change ask of our team? Timeline, training, and cost vary by provider, which is where a side-by-side comparison earns its keep.
What should you ask a phone provider before you choose one?
Ask every provider you are considering exactly what happens to an incoming call when Microsoft is unreachable, and what your staff would do to answer it.
- If Teams is unavailable, where do calls to our main number go?
- Does that switch happen automatically, or does someone on our side need to trigger it?
- Can staff make and take calls in your own app or on desk phones without Teams running?
- If your platform has an outage, how do calls reach us, and can they forward to mobile numbers?
- How many data centers carry our service, and what happens to our calls if one goes offline?
- How do you notify us during an incident if our email is down too?
- Can we test failover together, and how often do you recommend it?
The bottom line
November 12 showed how much of a workday can depend on one platform. You cannot prevent a provider's outage, and no provider is immune. You can decide how much of your communications any single outage is able to reach, and you can prove the backup works with a ten-minute test.
If you want a second set of eyes, Maverick is a supplier-neutral advisor. We help you compare options, plan a diversified design, and coordinate the work with your providers from evaluation through go-live and after.
