Vectors are the best file types to use for UI design because they scale to any size without quality loss. This particular icon set created by Vecteezy features mobile connections & wi-fi signals from many devices in the modern flat style.
The full iconset is released under Creative Commons which allows designers to incorporate these icons into any project, commercial or otherwise. Plus these icons have been released exclusively on Web Design Ledger which makes them unique and all-the-more exciting to UI designers.
Be sure to download this pack and spread the word on social media to bring more attention to this quality freebie.