Share a mechanism to make a remote rtsp stream from webcamera

The task is to enable rtsp video streaming from laptop's webcam so that it can be watch in VLC player in other network. The criterion of successfully completed task is the following situation: 1. I turn the webcam on my laptop on. It starts streaming 2. I can see the stream on my smartphone wthich is NOT connected to the same network (WI-FI) as my laptop.