This is a RS-232 Female icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 12,300 icons, all in the same style and quality.
This looks like an upside down trapezoid. The corners of the trapezoid are rounded. In the center of the trapezoid are nine circles. There's a line of five circles near the top of the trapezoid, and a line of four circles near the bottom.