The basics are that you have to set the IP and sip ports on the doorbell and phones to be static. Then under the doorbell settings of the 3710 you tell it to call the IP address and Sip port of the phone you want to get the video call. There’s a limit of 5 with this method.
I have a zip file with the screen shots but it won’t let me upload it here or in a PM. PM me your email address and I’ll send it to you. it’s only about 974kb