Why can't I send any type of text message over wifi

[AC Question]

I have a Samsung Galaxy S111 purchased as a sprint phone. I upgraded to Verizon and purchased a new phone and now want to give this phone to my special needs son but no longer so he can send text messages over wi-fi to his friends. In its current state, I can search the Internet over wi-fi no problem, but all my attempts to send text over wi-fi have failed. These include trying to send text on SMS, MMS, and gochat pro. I don't want to set up kik messenger or other similar social apps for obvious reasons. Is there a work around or does Sprint automatically disable the text over wi-fi when you no longer use their service? I have spent hours trying to figure this out and can't seem to find a solution. Is there one???