I have an iPhone X running iOS 13 beta 5. ATT is my service provider. I have turned off cellular data. I have also turned off Wi-Fi calling. I just tried texting two people that have android phones and they were able to receive my texts. The text bubbles on my phone are green and yet my wife sitting next to me receives the text on her galaxy phone just fine. How is this possible? It works whether or not I turn iMessage on or off.