Hi @Davide Maccagno
When using Teams Phone Mobile, please ensure your organization has the following Microsoft 365 services:
- Teams Phone SKU or E5 with Teams
- Teams Phone Mobile add-on SKU
To enable phone number assignments with Teams Phone Mobile, make sure your users:
Have Teams Phone and Teams Phone Mobile licenses. To learn more, see What is Phone System? and Assign Teams add-on licenses to users.
- Have an eligible mobile subscription with your preferred operator that supports their SIM-enabled phone number to be used for Teams Phone. Your operator will upload the phone numbers to your Microsoft 365 tenant.
- Are in TeamsOnly mode. Users must be in TeamsOnly mode, but your entire organization does not. To learn more, see Understand Microsoft Teams and Skype for Business coexistence and interoperability.
How you manage phone numbers depends on whether you're setting up numbers for new users, or moving existing numbers from Microsoft Calling Plans, Operator Connect, or Direct Routing.Please refer to Manage phone numbers for Teams Phone Mobile.
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