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ACS UK phone number in Dynamics 365 Voice routes to an unrelated third party, and Phone numbers blade now shows “Server not responding”

Luna Zhang 0 Reputation points
2026-04-23T18:19:28.7433333+00:00

Hi, I am setting up Dynamics 365 Voice / Omnichannel for Customer Service for the first time and I am trying to use an Azure Communication Services (ACS) UK phone number for inbound voice testing.
Here is the full setup and what happened step by step:
I enabled the Voice channel in Copilot Service admin center.

  1. I connected Dynamics 365 to a new Azure Communication Services resource.
  2. I created the required Event Grid app registration and connected the ACS resource successfully in Copilot Service admin center.
  3. I purchased a UK geographic phone number through ACS:
  4. I synced the number into Copilot Service admin center and connected it to a voice workstream.
    • The number shows as Connected
      • It is assigned to my inbound voice workstream
      1. I created a Voice queue and added the customer service users to that queue.
  5. I configured the voice workstream with:
  6. In Azure, I confirmed that the following Event Subscriptions were created successfully for the ACS resource:
  7. At this point, from the configuration side, everything appeared to be connected correctly.

However, when I called the ACS number from my mobile phone, the call did not go into Dynamics 365 / Omnichannel. Instead, it was answered by an unrelated third party / stranger. And I'm pretty sure I didn't dial the wrong phone number.

I then checked the Azure Event Subscription metrics for both:

  • IncomingCall
  • RecordingFileStatusUpdated

During the test call, the metrics remained at 0 and showed no activity, which makes it look like the call never entered our ACS / Dynamics 365 voice flow at all.

Also, after this, when I go back to the ACS Phone numbers page in Azure Portal, the blade now shows an error: “Server not responding. Unable to access phone numbers right now. Please try again later.”

So at the moment I have two related issues:

  1. The purchased ACS UK phone number appears to route to an unrelated third party instead of our Dynamics 365 voice workstream
  2. The ACS Phone numbers page in Azure Portal is now in an error state

Has anyone seen this before with ACS UK numbers? Could this be a PSTN routing / provisioning issue on the ACS number itself rather than a Dynamics 365 configuration issue?

Any guidance would be appreciated.

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2 answers

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  1. Golla Venkata Pavani 5,745 Reputation points Microsoft External Staff Moderator
    2026-04-23T20:06:21.0366667+00:00

    Hi @Luna Zhang

    Thank you for reaching us regarding the issue is not caused by Dynamics 365 Voice configuration and instead indicates that the inbound call is not reaching Azure Communication Services (ACS).

    Azure Communication Services integrates with Dynamics 365 Voice using Azure Event Grid, where inbound calls generate the Microsoft.Communication.IncomingCall event. This event is required for applications (such as Dynamics 365 Voice) to receive and process incoming calls.

    • A PSTN call made to a phone number owned by an ACS resource must trigger an IncomingCall event
    • Event Grid then delivers this event to the configured webhook endpoint
    • Dynamics 365 Voice routes the call to the workstream based on this event

    Event Grid showing no IncomingCall events indicates the PSTN call is not reaching your Azure Communication Services resource, ruling out a Microsoft Dynamics 365 configuration issue since Dynamics depends on that event. The “Server not responding” error also points to a possible ACS backend or service issue, consistent with calls not being delivered and no events generated.
    Recommended Steps:
    Validate the phone number via CLI or portal

    • Check whether the phone number is visible and associated with your ACS resource 
        az communication phonenumber list --connection-string "<yourConnectionString>"

    Use the “Number lookup” feature in Azure portal

    • Confirm the number is recognized and has full voice capabilities

    Check Azure Service Health

    • Verify whether there are any active incidents affecting Azure Communication Services.

    Reference:
    https://learn.microsoft.com/en-us/azure/communication-services/quickstarts/telephony/get-phone-number?tabs=windows&pivots=platform-azcli
    https://learn.microsoft.com/en-us/dynamics365/customer-service/administer/voice-channel-acs-resource

    Kindly let us know if the above helps or you need further assistance on this issue.

    Please "accept" if the information helped you. This will help us and others in the community as well.

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  2. AI answer

    2026-04-23T18:19:58.7733333+00:00

    The behavior described cannot be fixed from the Dynamics 365 configuration side alone and indicates an issue with the Azure Communication Services phone number provisioning/routing.

    From the Dynamics 365 side, the setup is already aligned with the documented flow:

    1. A voice channel is deployed and connected to an Azure Communication Services resource using either a new or existing resource.
    2. The ACS resource is successfully connected in Copilot Service admin center with Event Grid app ID and tenant ID, and the Omnichannel web hook endpoints are created for incoming calls, recording, and SMS.
    3. The phone number is acquired in ACS, synced into Dynamics 365, and then assigned to an inbound voice workstream and queue.
    4. After sync, all previously acquired numbers appear on the Phone numbers page and can be used for routing in Dynamics 365 Contact Center.

    When all of the above is in place and the number shows as Connected and assigned to a workstream, but:

    • No IncomingCall events are emitted from ACS (metrics stay at 0), and
    • The call is answered by an unrelated third party, and
    • The Phone numbers blade in the Azure portal shows a generic error ("Server not responding. Unable to access phone numbers right now"),

    this points to a PSTN provisioning/routing problem with the ACS number itself rather than a misconfiguration in Dynamics 365 Omnichannel. Dynamics 365 only receives calls once ACS has correctly associated the PSTN number with the Communication Services resource and is emitting the corresponding events.

    Because number provisioning, PSTN routing, and portal errors on the Phone numbers blade are handled entirely by the Azure Communication Services platform, this scenario requires an Azure support case so that the ACS engineering/support team can:

    • Verify that the UK geographic number is correctly provisioned to the intended ACS resource and tenant.
    • Check PSTN routing on the carrier side for that number.
    • Investigate and fix the backend issue causing the Phone numbers blade to fail to load.

    No additional configuration changes in Dynamics 365 Contact Center or Copilot Service admin center are documented that would resolve a situation where calls never reach ACS (no events) and instead terminate at an unrelated third party.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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