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RTT (Real-Time Text) is a communication protocol that allows text to be transmitted instantly as it is typed or created. This technology is particularly useful for individuals who are deaf or hard of hearing, as it enables real-time communication without the delays associated with traditional text messaging. RTT is often integrated into modern communication devices and platforms, providing an accessible and efficient means of communication for those who rely on text-based interactions.

All Phones Are Getting a New Feature! Hardly Anyone Knows About It

Making phone calls while simultaneously sending messages? With RTT, this will soon be standard.
Making phone calls while simultaneously sending messages? With RTT, this will soon become standard. Photo: Getty Images

July 6, 2025, 1:09 pm | Read time: 2 minutes

Real-Time Text (RTT) combines chatting and calling in real time and will be introduced in all German mobile networks starting June 2025, as mandated by the Accessibility Strengthening Act.

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Separate communication via mobile phone is a given today. Messages are sent via SMS or messengers like WhatsApp. But now there’s a new service that combines chatting and calling, taking it to a whole new level. The service is called Real-Time Text (RTT) and is already available on some current smartphones. RTT is designed especially for people with disabilities and will be introduced in all German mobile networks starting June 28, 2025.

What is Real-Time Text?

RTT allows you to send and receive texts in real time during a phone call. Current smartphones–such as iPhones with iOS 18.5 and some Samsung models–already support this technology. No additional app is required, and the integration is done through the Accessibility Strengthening Act (BFSG), which will take effect on June 28, 2025, in accordance with EU Directive 2019/882.

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How does RTT work?

During a call, you can switch to RTT mode if the recipient’s smartphone also supports RTT. A button appears on the display, allowing you to type chats that appear in real time to the person you’re speaking with. The call remains active, and it is not a conversion of text to speech.

The texts appear immediately to the recipient, making communication much faster and more direct than SMS or messenger chats. The colleagues at COMPUTER BILD have already tested RTT, and it worked on both an iPhone with iOS 18.5 and a Samsung with the beta version of OneUI 8.0. On the iPhone, users must first enable the feature in settings to start RTT calls. However, incoming RTT calls work without activation.

  • iPhone: The feature is located in the settings under Accessibility.
  • Samsung: Activation is done through the phone app under detailed settings, accessible via the three dots in the top right. There you will find the entry Real-Time Text.

Starting mid-2027, RTT will also be mandatory for emergency calls. Communication via text will be possible through emergency numbers 112 or 110, which is extremely helpful in dangerous situations where speaking is not possible.

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Which devices support RTT?

All mobile devices released from June 28, 2025, onward must support RTT. There are no strict requirements for existing models, but Telefónica plans to gradually make older devices RTT-capable through software updates, according to a press release.

This article is a machine translation of the original German version of TECHBOOK and has been reviewed for accuracy and quality by a native speaker. For feedback, please contact us at info@techbook.de.

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