As a Verizon, Tmobile, or Att customer you might be able to get 1gbps down .. but why do you need that on your phone?
Why are they popular? It makes little sense to pay $90 a month per line. With MVNOs the price is about 20-30$/mo. (Options out there: StraightTalk, USMobible, Lycia, Mint, Visble, Ting, Google FI, etc) Some of these carriers are even getting in international calling and roaming at an affordable price.