why is the title bar blue and the call button is greyed out within the chat for this co-worker?

Hi Jason,

Welcome to the Microsoft Q&A forum.

Thank you for contacting us. I would like to provide the following information:

1. Regarding the Title Bar

If you would like to change the title bar to a dark blue color, please follow these steps:

• Open Settings in Microsoft Teams.
• Select Appearance and accessibility.
• Under Theme, choose Classic.

After changing the theme, the title bar color should switch to dark blue.

2. Regarding the Call button being greyed out

This behavior can occur for one of the following reasons:

1. Your colleague may be using a personal Microsoft account or an external account.
2. Your administrator may have configured a Teams policy that disables calling within Teams chats.

To help investigate this issue further, could you please provide the following information?

• Is your colleague's account in the same Microsoft 365 tenant as yours?
• Does the issue also occur when both you and your colleague use Teams on the web?
• Is the Call button greyed out only for this colleague, or does it affect other users as well?
• Please contact your tenant administrator (typically your IT department) and ask them to verify whether any Teams policies are restricting or disabling the Call button.

I hope this information is helpful

If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.

I look forward to continuing the conversation.

If the answer is helpful, please click "Yes" and kindly upvote it.

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