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Unable to add person to Teams meeting

Joao Custodio 21 Reputation points
2025-08-04T15:05:36.4166667+00:00

Hi,

I have users not being able to add some participants to Teams meetings with the iPhone Teams app,

When they try to add a participant a message saying "Unable to add this person / This person might be using Skype for Business and can't be added to this chat."

User's image

I'm not sure if the other person is using Skype but I think it's unlikely, but even if they are, shouldn't we be able to add them to a meeting?

I have Teams on latest version and Coexistence mode set to Islands

Thanks for your help!

Microsoft Teams | Microsoft Teams for business | Meetings and calls | Schedule meetings
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Answer accepted by question author

Anonymous
2025-08-04T16:13:45.0733333+00:00

Hi @Joao Custodio 

 

Thank you for reaching out regarding the issue with adding participants to a Teams meeting via the iPhone app. 

 

Based on the error message and your current setup, it appears that the participant you're trying to add may still be using Skype for Business, possibly in an on-premises environment. 

 

Since your organization is currently operating in Islands mode and Hybrid Connectivity has not been configured, Teams is unable to discover or federate with Skype for Business users. This is because hybrid interoperability relies on Lync DNS discovery, which is not active in your environment. 

 

Here are some additional steps we recommend you take to mitigate the problem. 

  1. Confirm the participant’s platform: 

Ask the external user if they’re still using Skype for Business (especially on-prem). 

If they are, they may need to join via Skype or be invited via email instead of added directly in-app. 

 

  1. Configure Hybrid Connectivity 

Set up hybrid connectivity between Skype for Business on-prem and Teams. This involves: 

  • Ensuring proper DNS records for Lync discovery. 
  • Configuring federation and SIP routing. 
  • Validating firewall and proxy settings. 

Microsoft has a Hybrid Connectivity guide that walks through the steps: 

  1. Migrate Users to TeamsOnly Mode (If your organization is ready to fully move to Teams) 

Switch users from Islands to TeamsOnly mode. 

Step 1: Access the Microsoft Teams Admin Center 

Step 2: Find the User 

  • Navigate to Users > Manage users. 
  • Search for the user by name or email address.  image

Step 3: Open the User’s Profile 

  • Click on the user’s name to open their details page. 

Step 4: Change Coexistence Mode 

  • In the Teams upgrade section, look for Coexistence mode. 
  • Click on Edit.  User's image
  • Select TeamsOnly from the dropdown menu. 
  • Click on Apply to apply the new settings.  User's image

After the Change 

  • The user will now use Microsoft Teams exclusively for chat, calls, and meetings. 
  • Skype for Business will no longer be available for that user. 
  • You can follow this guide to update user settings:  Upgrade Skype for Business On-Premises to Teams 

In the meantime, as a workaround, you can try inviting the participant via their email address using Outlook or the Teams desktop app instead of adding them directly through the mobile app. 

Please let me know if you'd like assistance or if you have any further questions. 

Warm regards, 

 

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". User's image

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