When calling in to Microsoft Teams the Teams client does not ring. The user has the dial pad and can make outbound calls.
Calls fail. The portal shows a 404 Unallocated Number error.
2021-05-07 14:57:01 (UTC) SIP processing error Invalid argument 404 2021-05-07 14:57:01 (UTC) Reason header: Q.850 ;cause=1 ;text="3e5815f1-6343-4602-b941-3653b352e2ba;RNL" 2021-05-07 14:57:01 (UTC), new state => Closing Error, accepted => Y 404 Not Found
Solution Part 1
1. Allocate a random/different number for the user in the service portal.
2. Click on the sync button to run a fresh sync.
3. Wait for up to twenty minutes for the changes to propagate.
4. Allocate the correct user number.
5. Click on the sync button to sync again.
Solution Part 2
1. Remove the Microsoft 365 Phone System licence from the user in the Microsoft admin portal.
2. Wait at least 20 minutes for the change to propagate.
3. Restore the Microsoft 365 Phone System licence to the user in the Microsoft admin portal.
1. Log in to the Office 365 admin portal at https://www.office.com/
2. Go to the Admin icon.
3. On the left hand side menu bar select "Show All" to see the Support option.
4. Create a new support request with an appropriate title such as "Unable to receive calls in Teams (404 error)"
5. Within the detail of the support request, provide the following details:
- A User email address for one of the users with dial-pad that cannot receive calls
State the following in the ticket:
- Direct Routing is being used in Carrier Mode (SBCs will not show in the Teams Admin centre)
- Enterprise Voice is enabled for the user
- The Voice Routing Policy is applied to the user
- The User has a valid Phone System licence
- The user can place outbound calls
- The correct number is showing on the Teams admin centre and the user’s dial pad
- Microsoft Approved Direct Routing SBCs are being used.
- The calling service/trunk is getting a 404-rejection error from Microsoft Direct Routing when sending the call to Teams with messages such as "Reason header: Q.850 ;cause=1 ;text="4c5ea470-5ff3-4489-a9bc-7207c168c5f7;RNL" <- (insert a relevant code here)
If Microsoft request SBC logs then refer to support to have these provided.