Idea of Mobile Icon
The icon is shaped like two horizontal rectangles. Inside each rectangle are smaller rectangles that start at the top and end almost at the bottom right before meeting a dot and the bottom center. Both rectangles are the same size but the left one is partially hidden behind the right one.
This page shows the different variations of the Mobile from an Icons8 icon pack. Feel free to resize and recolor the icon, and then download the icon in PNG format for free.