Once you are connected with your patient, to add another participant, click on the '+ person' icon at the bottom of the screen.
This will initiate the option on your desktop to click on 'Patient Hand-Off'.
This allows you to pass your patient off to another clinician or specialist. You will then see the option to either stay on the video call or hang up.
Inviting a 3rd person by selecting 'Patient Hand-Off' does not expose your personal cell number to either party.