Who I have the same questioned this topic

I am travelling internationally.  Even with airplane mode enabled, when I am connected to wifi, I have been able to send and received text messages.  I am using the messaging app that came with my Note 8, not the Verizon one.  The bar on top shows the airplane and the wifi symbol, but not the VZN wifi.  Is this possible?  I just want to make sure that I will not received any roaming charges on my account.  I did a quick search online, I keep reading contradicting information.  Some said this shouldn't work unless you are roaming, that it only works with VZN messenger app, to it works.