You can use the TTY, or teletype, feature on your iPhone. This feature helps deaf and hard of hearing people hold phone conversations and reading texts. To be able to use this, you need to have the iPhone TTY Adapter (Apple iPhone TTY Adapter). Also make sure that the TTY setting on the phone is turned On (Settings > Phone).
Related:
- All about Accessibility: Accessibility features of iPad / iPhone and iPod
- How to Turn On Closed Captioning for iPhone, iPad, and iPod Touch and Find Movies
