Communication Workers of America is probably the closest to what you're looking for. You're definitely better off working with an established union instead of trying to build one from scratch, they have a lot of valuable experience and resources that you'll need to pull off a unionization attempt. If you reach out directly to CWA, or any other union, they'll work with you to help organize your workplace.
If you are serious about unionizing: first, see if you can get a few of your coworkers on-board by talking to them outside of work. Do this in-person or on voice calls that aren't recorded, it's crucial to keep the company unaware as long as possible so they have less time and ability to oppose you.