How can I enable WiFi calling on an iPhone 4S? iPhone 4S (VZN Model) with IOS 9.3.2 unlocked and works with TMO.  What is the procedure / process to configure it for wifi calling.  As I understand it IOS 8 supports wifi calling.

As Bill Tanner has graciously pointed out, Apple indicates a 5C or newer model is supported.  I suspect that the 4S has the hardware necessary to perform wifi calling.  If this is not the case, I'd like to understand the gap that prevents wifi calling: I have successfully made SIP calls (a form of wifi calling) with the device. 

I do not believe this to be a duplicate of the question posed regarding the iphone 5   The question is not whether 4S is supported for wifi calling, but what (if any) procedure would be needed to enable wifi calling functionality.  It would not surprise me this feature is feasible with the 4S and that Apple is in a position to easily add it to the list of model that are valid for wifi calling code / instructions

Insight into the procedure to enable wifi calling on the 4S would be appreciated.  Thank you
You need a 5c or later to use WiFi Calling.

https://support.apple.com/en-us/HT203032