If you searched for "Microsoft Teams unable to make or receive calls," the real picture is narrower than that phrase suggests. BleepingComputer reported two separate problems on Sept. 4, not one sweeping outage: some Windows users couldn't get the Teams desktop client to open, and separately, some Mac users were blocked from joining calls and meetings.
This isn't a case of Teams calls not working across the board. The incident descriptions do not establish a Teams-wide outage; Microsoft's notices don't say how many users or app versions were affected, and the two problems carry different incident numbers, symptoms, and guidance.
What follows breaks down each Microsoft Teams issue by platform, what Microsoft said to do about it, and where the reporting leaves gaps.
If Teams won't open on Windows
Microsoft logged the Windows problem as incident TM1466820 at 4:45 p.m. EDT on Sept. 3, according to BleepingComputer.
"Specifically, when first opening Microsoft Teams on Windows devices, some users may be initially unable to load the client or may encounter loading delays of up to two minutes," Microsoft said in an incident report, according to BleepingComputer.
That's launch behavior, not a calling-feature bug. The quoted notice addresses opening the desktop app on Windows and does not mention call quality, audio, or meeting behavior once the client is running.
In the Sept. 4 update, Microsoft said its analysis of service logs and telemetry had been inconclusive, and it had reached out directly to some affected users while working to identify the cause.
Microsoft's stated workaround for TM1466820 was Teams on the web or the Teams mobile app: "While we're focused on remediation, affected users may be able to avoid impact by using Microsoft Teams on the web or alternative Teams access methods such as the Teams mobile app," according to BleepingComputer.
That's a hedged fix, "may be able to," not a guarantee, so treat it as a fallback Microsoft recommended rather than a confirmed cure.
Microsoft Teams cannot join calls or meetings on Mac: what Microsoft reported
The Mac issue was a separate incident, tracked as TM1466659. A Microsoft service-health record mirrored by the University of Pennsylvania lists the incident as resolved, with impact running from Aug. 23 through Aug. 26.
Microsoft's wording was specific: "Users may be unable to join calls or meetings in Microsoft Teams for Mac," according to BleepingComputer.
That's narrower than "Teams calls not working" might imply. The notice describes joining calls or meetings specifically and doesn't establish whether the problem also touched placing outbound calls, receiving inbound calls outside scheduled meetings, or launching the Mac app in general.
A Mac that opened Teams normally but failed specifically when joining a call was consistent with the description Microsoft published.
During the investigation, Microsoft said it was "reassessing our root cause understanding and reviewing service logs to isolate the source of impact, so that we can determine our next steps regarding impact remediation," according to BleepingComputer.
Microsoft later finalized the incident record and attributed the problem to a code change that caused the service infrastructure responsible for call and meeting functionality to fail to process some requests. Microsoft said it deployed a fix and confirmed the impact was resolved after monitoring service availability.
Which symptom matches which incident
Windows desktop app won't open, or takes up to two minutes to load: matches the description Microsoft gave for TM1466820, with the web or mobile workaround Microsoft recommended at the time.
Mac app opens normally but fails specifically when joining a call or meeting: matches the wording Microsoft used for TM1466659. Microsoft later marked that incident resolved.
Ordinary outbound or inbound calling outside of joining a scheduled meeting: not addressed by these two incident descriptions.
What the reports don't tell you
Both incident notices described impact on "some users," language that stops short of confirming a failure across all users.
The Sept. 4 BleepingComputer report did not identify an affected app version for either incident or a resolution timeline for the Windows issue. Microsoft later published more detail for the Mac incident, including its final root cause and confirmation that the impact had been resolved.
For comparison, when Microsoft resolved a Teams Android issue that blocked some users from making outbound calls over the phone network, the final report named the exact client version involved, described the root cause as a code change that mishandled dialed-number formatting, and included a completed fix timestamp.
That 2023 incident affected Android client version 1416/1.0.02023092901/0516. Microsoft said a code change incorrectly prepended a "+" to dialed numbers, interfering with the library used to normalize numbers and prepend country codes.
BleepingComputer also mentioned two other Teams problems from earlier in 2026: an April issue that prevented some Microsoft Teams Free users from chatting or calling others, and a separate bug that caused Teams and New Outlook launch failures on certain ARM-based Windows devices after Windows security updates released since the August 2026 Patch Tuesday.
Neither was identified as the cause of TM1466820 or TM1466659. Microsoft has since fixed the ARM-based Windows issue, saying Windows updates released Sept. 8 and later resolved it.
What to do now
Match the symptom guide above to what's actually happening on your device.
If Teams won't open on Windows, or takes an unusually long time to load, Microsoft's recommendation for TM1466820 was switching to Teams on the web or the mobile app.
If a Mac is failing specifically when joining a call or meeting now, don't assume TM1466659 is still responsible. Microsoft has marked that incident resolved, so a current failure may have a different cause.
The reporting behind this article describes specific incidents from late August and early September, not the live status of Microsoft Teams today. For current information, check Microsoft's Microsoft 365 service health tools or contact your organization's administrator before treating either incident as active.
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