"It was a setting in the GXV3470 IP Video Phone Call Settings called Auto Preview. Turned it on with Ringing feature so the phone still rings on an incoming door station call but you can see video without answering. Working perfect.
I now have both the 3470 desk phone and the 3570 indoor station both ringing when someone presses the call button at the door and both show preview video before answering. Either one can answer the call, have video and 2 way audio and unlock the door."