To dial a number from Teams, go to Calls , click Dial a number, and then enter the number of the person you want to reach. This way you can contact anyone, even if they're outside your organization.
In the Calls area, you can also access favorite and suggested contacts, listen to your voicemail, and check your call history.
To make a call, tap Calls > Dial pad and enter a phone number. If you’ve enabled the setting to allow access to your phone contacts, tap Calls > Contacts and select a contact.
To call a phone number (PSTN) from the Surface Hub, touch Call from the welcome screen, and then tap Dial Pad.
Once you’ve accessed the dial pad, just enter the number you want to call.