has Teams URL referrer changed again ?

Smyth, Michael (ESS) 0 Reputation points
2026-08-06T16:52:55.8633333+00:00

We currently cannot get our Cisco VC units to join a MS Teams meeting. We've tried OBTP and also entering the MeetingID details but nothing. The Screen appears to attempt connecting to the meeting but then just hangs. Screen goes white and will try forever to join. On the Control Hub, the unit appears as 'on a call' but isn't.

Has there been another change to any URLs recently. We are aware that June 5th there was a new URL - [Moderator note: Personally Identifiable Information removed] that we had to add to our allow list.

Also I can't find a definitive place where MS publish all the IPs and URLs. It says MS issue 30days advance notice of changes but no idea where this would be.

Any advice would be much appreciated.

Microsoft Teams | Microsoft Teams for business | Meetings and calls | Audio and video
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  1. Lin v 250 Reputation points Independent Advisor
    2026-08-06T17:44:14.85+00:00

    Hi Michael,

    Thank you for providing the details. From your description, it sounds like you've already done some of the common checks, including allowing the teams.public.onecdn.static.microsoft URL that was introduced earlier.

    Based on what you've described, I'd suggest checking a few things first:

    • Compare your current firewall/proxy allow list against the latest Microsoft 365 endpoint documentation. For reference: Microsoft 365 URLs and IP address ranges - Microsoft 365 Enterprise | Microsoft Learn.
    • Review firewall and proxy logs during a failed join attempt to see whether any Microsoft Teams or Microsoft 365 endpoints are being blocked.
    • Confirm the affected Cisco devices are running a supported and up-to-date RoomOS version.
    • Capture timestamps from a failed join attempt and review any diagnostics available in Cisco Control Hub.

    However, based on the symptoms you've described:

    • OBTP and manual Meeting ID joins both fail
    • The device appears to begin connecting
    • The screen turns white and remains stuck
    • Cisco Control Hub shows the endpoint as "on a call"

    It is difficult to determine whether this is related to networking, Cisco interoperability components, or the Teams service itself.

    Please note that, as an Independent Advisor, I do not have access to Microsoft service telemetry, tenant diagnostics, backend logs, or Cisco Control Hub diagnostics, so I am unable to identify the root cause based on the information available in this thread.

    Given that, I would recommend opening support cases with both Cisco and Microsoft. Cisco can investigate device-side behavior, RoomOS/CVI diagnostics, and Control Hub data, while Microsoft can review Teams-side diagnostics and service behavior. Having both vendors engaged often helps accelerate resolution because each has visibility into different parts of the call flow.

    For guidance on how to request support from Microsoft, please refer to: Get support - Microsoft 365 admin. 

    Note:

    • If your account does not have administrative permissions, you’ll need to contact your IT administrator to submit a support request on your behalf.
    • If you are unsure who your IT administrator is, you can refer to this official Microsoft guide for assistance: How do I find my Microsoft 365 admin? - Microsoft Support.

    Regarding the information about endpoint updates, you may find the links Microsoft 365 URLs and IP address ranges - Microsoft 365 Enterprise | Microsoft Learn and Microsoft 365 Endpoint Web Service helpful, as these are Microsoft resources that publish Microsoft 365 URL and IP information.

    I hope everything gets sorted out soon. Please feel free to reach out if you need further assistance.

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