Currently TracFone using T-Mobile's network. But TracFone was bought out by Verizon and Verizon is discontinuing some of the 4G bands in favor of 5G.Whose network do they run on?
US Mobile can use any network, T-Mobile, ATT and Verizon. So my current phone can work with them without doing anything but getting a new sim card. But I'm not opposed to using the Verizon network as they have better coverage in my area. I just won't get their service directly through them as it's a minimum 5x the cost