Flashing Vodafone firmware on Galaxy S6

Hello, i have a Galaxy S6 that i bought from Carphone Warehouse which is unlocked. I am on a vodafone contract and want to be able to use WIFI Calling. I have been told that it will only work if i bought the phone directly from Vodafone. After some research i found on sammobile that the official firmware is availble on Vodafone. If i were to flash this file, would it activate the features? Would this reset the phone or void my warranty?

sammobile.com/firmwares/download/73864/G920FXXS3DPF5_G920FVFG3DPC1_VOD

Thanks