Refer to Set the phone numbers included on invites in Microsoft Teams. Step 3 - Change the default phone numbers that are included in the meeting invites of users (optional) Highlight the service toll number that you want to configure as the default. On the left navigation pane, go to Meetings > Conference bridges. If you are assigning a service toll number and you would like to set it as the new default number for your audio conferencing bridge, perform these steps: Only a service toll number can be set as the default number for your conferencing bridge service toll-free numbers can't be set as the default number of your conferencing bridge.

The default phone number of your conference bridge defines the caller ID that will be used when an outbound call is placed by a participant or the organizer from within a meeting. Step 2 - Change the default phone number of your conference bridge (optional) On the Edit page, under Assigned to, expand the dropdown and then select Conference bridge > Apply. Select the phone number from the list, and click Edit. On the left navigation pane, go to Voice > Phone numbers. Step 1 - Assign the new phone number to your audio conferencing bridge

Except where it's called out otherwise, all these steps must be performed in the Microsoft Teams admin center.

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