Repeated contacts rise to the level of stalking when they’re designed to gain power over a person and cause emotional terror.
Stalkers often emphasize that they “love” their victims and occasionally say they stalk to keep others safe.
If the person in your phone book, the Knock Knock feature provides live video before you pick up. Turn it back on and video should return, too— though it doesn't always cooperate.
So it's almost definitely not a nude stranger.
Stalkers may alternate between patterns of domestic violence and stalking.
Each state establishes its own legal criteria for stalking.
I don't recognize the number, but that's normal.
What's weird is it's a video call, from someone using Duo, Google's video chat app available today for i OS and Android.