how do i add a trusted organization?

Hi Romeo,

If you're referring to adding another company as a trusted organization in Teams so you can chat, call, or meet with users from that organization, you'll need to contact your Global admin or Teams admin, as this is configured at the tenant level.

In case you do not know who is your IT admin, kindly refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support

For Teams External Access, your administrator can add the organization's domain in the Teams admin center:

• Go to Teams admin center > External collaboration > External access.

• Under Choose which domains your users have access to, select Allow only specific external domains.
• Select Allow domains.

• Enter the external organization's domain and select Done.
• Repeat for any additional domains if needed.
• Select Save.

You may share this guidance with your admin for reference: Onboard trusted vendors to collaborate in Microsoft 365.

I hope this information is helpful. Let me know if you have any questions.