Palm Pre P100EWW - Manual (Page 61)

Chapter 4 : Phone 61
You can connect a TTY/TDD machine to your phone using the headset
jack. Check with the manufacturer of your TTY device for connectivity
information. Be sure that the TTY device supports digital wireless
transmission.
NOTE When TTY is enabled, you cannot use the headset jack for anything else,
and all audio modes are disabled on your phone, including holding the phone up to
your ear and listening.
1 Connect a TTY/TDD device to your phone using the headset jack.
2 Open Phone .
3 Open the application menu and tap Preferences .
4 In TTY/TDD , tap Off to switch TTY/TDD from Off to On.