Imessage
iMessage continually switches over to sms texting even when one is on wi-fi and the other is on LTE network.
iPhone 6s Plus, iOS 11.1
iMessage continually switches over to sms texting even when one is on wi-fi and the other is on LTE network.
iPhone 6s Plus, iOS 11.1
Hello and welcome to Apple Support Communities, Yoyoma53.
If I understand your post correctly, your iPhone changes from iMessage to SMS texting depending on whether you or the person you're messaging with is on Wi-Fi or cellular. I'd like to help.
First, make sure that you're iPhone is fully up-to date, including any avaialble carrier updates. This article will show you how: Update the iOS on your iPhone, iPad, or iPod touch
Then make sure that iMessage is set up as shown here: Use iMessage apps on your iPhone, iPad, and iPod touch
Let us know if that resolves this issue for you.
Thanks for using the Apple Support Communities. Take care.
Imessage