iPhones, WiFi Calling, and SMS/MMS Messaging

A friend using an iPhone w/o cellular service, but with WiFi Calling, found he'd missed a whole bunch of text messages from non-iPhone users. It appeared he could send and receive text messages to/from other iPhone users when on WiFi Calling, but not to/from non-iPhone users (e.g.: Android users).

Being the group "IT Expert" and the most knowledgeable about iOS, I was consulted. I didn't know, so I searched on it. Everything I found said iMessage when on WiFi Calling only worked between iThings, and not between iThings and non-iThings.

Now I've had somebody, in a discussion on a forum, tell me that's not true--that he does it all the time.

So which is it: Should text messaging (SMS/MMS) work between iThings and non-iThings, when the iThings are on WiFi Calling, with no cellular connection, or does it not?

TIA!

 

I'm using wifi calling from a cuple of years with no problems sending sms/mms to any body, IOS or Android.
Of course, i'd never use Iphone without cellular connection.

 

Ok, thanks. Must be all the information my search turned up was out of date.