Helpful answerYes, the galaxy S7 supports VoLTE, but you need to aktivate it.
Explanation of the aktivation of VoLTE.
1. From the home screen, navigate to: Menu -> Settings -> Applications -> Phone
2. In the settings for the phone you will find the following entry in the "Call settings" section: Settings for outgoing voice calls
3. Tap the entry and you will see the following options:
Use VoLTE if available
Do not use VOLTAGE
4. Make sure that the mark is set to "Use VoLTE"