1. Create a full sandbox of your Dialer org.
2. Log in to your sandbox.
3. From Setup, enter Dialer Settings in the QuickFind box, then select Dialer Settings.
4. Toggle the Dialer setting off, then back on again.
5. Finish setting up Dialer in your sandbox org.If you haven’t finished setting up Dialer, this includes adding Dialer to the utility bar, creating a Dialer permission set, and assigning the permission set to users.Note Whenselecting phone numbers in sandbox, each user can choose from the same list of dummy numbers.An error may occur if multiple users are assigned to the same phone number.