How to Use TTY on Your iPhone
You can use the TTY, or teletype, feature on your iPhone. The TTY feature helps hearing-impaired people hold phone conversations. You can use the iPhone with standard TTY devices by plugging a cable from the TTY device to an optional $19 iPhone TTY adapter and then plugging the adapter into the iPhone. Make sure that the TTY setting on the phone is turned On.

iPhone Glossary
FaceTime
Apple software that enables users with supported mobile devices to both see and hear each other during wireless conversations.

iPhone Glossary
iCal
Apple’s personal calendar application.

iPhone Glossary
iCloud
Apple’s wireless storage and synchronization service that keeps digital information updated automatically and wirelessly without user instigation.

iPhone Glossary
iOS 5
The operating system for mobile Apple devices released in June, 2011. With iOS 5, data updates and synchronization occur wirelessly through the iCloud.

iPhone Glossary
jailbreak
Altering an electronic device to remove default restrictions imposed by the manufacturer.

iPhone Glossary
Siri
A voice-controlled personal assistant application purchased by Apple and available exclusively on the iPhone 4S.