LG LX101 Owner's Manual page 69

Note:
In TTY Mode, your phone will display the TTY access icon when a TTY
device is connected to the headset jack.
Note:
If TTY Mode is enabled, the audio quality of non-TTY devices
connected to the headset jack may be impaired.
WARNING: 911 Emergency Calling
It is recommended thatTTY users make emergency calls by other means,
including Telecommunications Relay Services (TRS), analog cellular, and
landline communications. Wireless TTY calls to 911 may be corrupted
when received by public safety answering points (PSAPs), rendering some
communications unintelligible. The problem encountered appears to be
related to TTY equipment or software used by PSAPs. This matter has been
brought to the attention of the FCC, and the wireless industry and PSAP
community are currently working to resolve this.
Section 2B: Controlling Your Phone's Settings 55