My Thunderbolt and now my Note2 does simultaneous voice and data.
Is the Note4 able to do simultaneous voice and data?
From another thread :
Is the Note4 able to do simultaneous voice and data?
From another thread :
Verizon phones (the new ones) need VoLTE to do Voice and data. The old phones (like your thunderbolt and Note 2) had two radios to do it... So VoLTE wasn't needed. All newer phones have one radio so they need VoLTE otherwise no data and voice.