3CX and MS Teams Direct Routing Integration

Question

3CX and MS Teams Direct Routing Integration

Didier Derveaux 0

We have installed 3CX and configured Direct Routing.

When we call from PSTN to a Teams user, the phone app in MS Teams rings once or twice and then goes to voicemail, even if the user is available. In the call logs in 3CX, we see that the call is marked 'Busy'.

When we disable MS Teams calling for this user, the call comes in on the 3CX app and only goes to voicemail when the no response timer has passed.

When we call a queue, which this user is opted in, the call works fine. Also, when we create a Digital Receptionist, and connect to the extension, the call works fine.

Does anyone have an idea why the call goes to voicemail to soon when we call directly to the extension?

Kind regards

2 answers

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Answer 1

The issue you are experiencing with calls from PSTN to a Teams user going to voicemail too quickly, even when the user is available, could be related to the call routing settings in your Direct Routing configuration. When a call is marked as 'Busy' in the 3CX logs, it typically indicates that the call is not being routed correctly to the Teams user, possibly due to the user's status or call handling settings in Teams.

Here are a few things to check:

User's Presence Status: Ensure that the Teams user's presence status is set to "Available" when the call is being made. If the status is set to "Busy" or "Do Not Disturb," calls may be routed to voicemail.
Unanswered Call Forwarding Settings: Check the unanswered call forwarding settings for the user in Teams. If these settings are configured to send calls directly to voicemail after a short duration, it could explain the behavior you're seeing.
Direct Routing Configuration: Review the Direct Routing setup to ensure that the call routing policies are correctly configured for the user. This includes checking the PSTN usages and voice routing policies assigned to the user.
Call Queue and Digital Receptionist: Since calls to queues and digital receptionists are working fine, it may be worth comparing the routing configurations for these scenarios with the direct call routing to the user’s extension.

If the problem persists, consider reaching out to Microsoft support for further assistance with your Direct Routing configuration.

References:

Answer 2

Henry-N 6,020 Microsoft External Staff Moderator

Hi @Didier Derveaux,

Thank you for posting your question in the Microsoft Q&A forum. 

Regarding that you want to know why the call goes to voicemail to soon when we call directly to the extension. I’d like to ask a quick questions to better understand your situation and assist you more effectively:

Have you checked the call settings in Microsoft Teams to see how long the option “Ring for this many seconds before redirecting” is set?

If it’s set too low, try increasing the duration.

If after you have set the time higher but nothing change. To resolve this, Microsoft’s support team will need to step in. A technical support engineer can perform a remote session to investigate the situation verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis.

The Global Admin should create a service request with Microsoft support to get advanced technical assistance and diagnostics.

If you’re unsure who the Global Admin is within your organization, you can find guidance on locating them here: How do I find my Microsoft 365 admin? - Microsoft Support.  
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Thank you again for your time and understanding. While my initial response may not resolve the issue immediately, I’d like to gather more details about your situation so I can assist you more effectively.

I really appreciate your patience, and I’m here to help. Looking forward to your response!

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Didier Derveaux 0 Reputation points

2025-12-04T07:50:43.62+00:00

Hi Henry,

Thanks for your reply.

For clarity, it is the 3CX that does the call handling, and it is the 3CX voicemail that is triggered because there is a busy signal coming from MS Teams.

I did check the no answer timer, I have set it to 60 seconds, but still the call got forwarded to the 3CX voicemail after a few seconds. Even when I disable forwarding to the mailbox in Teams, the call triggers a busy signal and the call is sent to the voicemail on the 3CX.

When I'm fast enough, I can accept the call and there is 2-way audio.

I just wonder why MS Teams sends a busy signal to the 3CX system after a few seconds.

I already did a packet trace, but since everything going to Teams is encrypted, I did not get any wiser...
Didier Derveaux 0 Reputation points

2025-12-04T07:51:39.3066667+00:00

This is the call log in 3CX:
Didier Derveaux 0 Reputation points

2025-12-04T08:09:38.8+00:00

I have found the issue. I was testing by calling from my cellphone to my Teams number, but it was the Teams app on my cellphone that triggered the busy signal. When I logged out of Teams on my cell phone, the call came in on my desktop and it did not get forwarded to voicemail.
Henry-N 6,020 Reputation points Microsoft External Staff Moderator

2025-12-05T16:13:03.9133333+00:00
Hi @Didier Derveaux,

Thank you for your reply. I really appreciate the information you’ve provided so far.

Could you please try the following checks to help us narrow down the issue?

Have you tested calling from Teams to Teams only (without going through 3CX)?

If possible, sign in to Microsoft Teams on another phone and see if the issue persists. This will help us determine if the problem is related to the device settings.

I’d like to confirm whether there might be a setting on the phone that redirects Teams calls to voicemail.

I apologize for asking multiple questions, but gathering these details will help me assist you more effectively.

Thank you again for your time and understanding. I appreciate your patience, and I’m here to help. Looking forward to your response!

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3CX and MS Teams Direct Routing Integration

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