The reason I brought this up was today I had to work in a basement where I had cell signal only Wifi. My coworker who was with me had an iPhone texting away and me who tried to text my girl couldn't get a signal to send a text. I know what people are going to say, "use hangouts" but my girl isn't tech savy and only uses iMessage. Unfortunately hangouts doesn't let you use your own phone number to send text over Wifi. Any solutions out there?