use wifi for data but not phone? I have a Samsung Galaxy S4 and figured out how to connect to WiFi, but I want only the data to go through WiFi, not the telephone calls. (I have had trouble w/ phone over wifi; the data is fine though + it saves me money going through WiFi.)

Is there a way to do this?
aha, found it:

under apps -> settings -> connections, I can turn overall use of Wi-Fi on or off.



Then if I select "More networks", I get this screen:



and I can turn on or off "Wi-Fi Calling".

Tmobile has a note about it here: http://support.t-mobile.com/docs/DOC-5864