Bluegrass – To use the phone on Bluegrass, you’ll need to have them enable VoLTE on your line.
H2O (and many AT&T based resellers, such as Consumer Cellular) – If your phone has no data or if it’s running only on 3G, you may need to set the correct APN.
Verizon – To use the phone on Verizon, you’ll want to have them set the device as CDMA-less. If you’d like to use the Visual Voicemail feature, have Verizon enable Basic Visual Voicemail on your line. Or, to have your voicemails transcribed to text as well, have them enable Premium Visual Voicemail. Note that this is a service provided by Verizon directly.