This icon is for cellular network service. In the center, it has a straight vertical line with a small circle on the top of it, indicating an antenna. There's one small, unclosed circle around the top of it, then a larger circle around that one.
Related to Cellular Network Icon
Related icons are the icons with matching tags, as well as all mobile icons. All icons are in the same flat style. You can either download free PNG icons or buy SVG vectors