Wifi Calling ATT Iphone 6s on StraighTalk

Can I expect a wifi calling on the StraighTalk to work with a SIM unlocked ATT iphone 6?

If you have experience with using an ATT iPhone on the StraightTalk, please state which iPhone + IOS version you have tested with StraightTalk. If there were any changes required to the ATT iPhone configuration: the steps required to reproduce wifi calling would be of interest