This article explains how to turn off RTT on an iPhone. It also explains what RTT is and why you might need to use it.

Real-time text (RTT) is an accessibility feature of the iPhone that you can’t remove, but if you don’t need it, you can turn it off. The feature is turned on in your iPhone’s Accessibility settings.

Here's how to turn off RTT on an iPhone:

Scroll down and tap Accessibility.