Signal fall back during RTT call
I heard that, RTT is only supported on WiFi and LTE, what if my phone fall back from LTE to 3G while I'm making an RTT call?
iPhone XR, iOS 12
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It will work on 3G*** also
*** RTT and TTY aren’t supported by all carriers or in all regions. RTT and TTY functionality depends on your carrier and network environment. When making an emergency call in the U.S., iPhone sends special characters or tones to alert the operator. The operator’s ability to receive or respond to these tones can vary depending on your location. Apple doesn’t guarantee that the operator will be able to receive or respond to an RTT or TTY call.