The Plus is currently the only device that currently supports WiFi calling
"What is WiFi calling?"
WiFi calling is a feature that allows kids to make calls without using the data. If you're in a location where data is not so good, then WiFi calling may be the answer. This feature is provided by the service provider so make sure your provider has WiFi calling if you plan to utilize it.
"How do I enable WiFi calling on my Pinwheel device?
To enable WiFi calling, you would just need to swipe down from the top edge of the phone, then swipe down again to get all the settings expanded, once you're there you will just need to find the "WiFi Calling" switch and click it to enable it.