What's the best way to make my Samsung Galaxy S4 wifi only, not active on a cell network?

[AC Question]

I'm giving my old phone to my son, to use at school for work/research. I don't want the phone to be on a cell network. I've already changed the data usage to 'Wifi only' but wanted to make sure he can't use it for talk/text until he is allowed. Thanks.

 

[Techtein]

If you don't put a SIM/remove SIM from a provider, it will only work on WiFi. However, in doing so the smartphone won't have any cell coverage due to which no one can call/text your son.

Moreover, there are so many apps such as Viber, Facebook Messenger, etc. that work on WiFi and are replacements to regular texting/calling.