I must nitpick: Mr. One Mug effectively says you can't accelerate anything to superluminal velocity. That does not, however, preclude the existence of particles whose only existence is at superluminal velocity. Useless for travel, not useless for communications.
After all, the same equation says you can't accelerate anything to lightspeed, yet we talk by radio all the time.
(Now, the paradoxes are another matter.)
Not exactly. It is anything with rest mass (fermions) that can't be accelerated to lightspeed. We talk by radio using photons (EM radiation) which have no rest mass and can only exist at c... at least according to uncle Al and cousin Max.
ETA:
Now if you come up with a way of using tachyons (which may or may not exist) for communication it would earn you Nobel prizes in a couple different fields.
Fermions--always below lightspeed. Photons--always at lightspeed, but we can manipulate them to great benefit. Tachyons, if they exist, would obviously always be above lightspeed. We have no evidence of them--but neither do they go against physics. When the rules permit something there's a good chance it exists.