You can select a different number to calling in two ways:
At the keypad screen enter the destination number you want to call
and tap on the “Calling from” number.
Select the number you want to use when calling.
Wait for the app to make the connection.
Tap on the contacts icon.
Select a contact to see more details.
Tap on the “Using number” button.
Select the number you want to use when calling.
Wait for the app to make the connection.