When TTY (teletypewriter) settings are enabled, you can use your phone with a TTY device if you're deaf or hard of hearing.
En la pantalla de inicio, oprime Apps (ubicado en la parte inferior).
Oprime Configuración. If unavailable, tap the dropdown menu (located in the upper left) then tap Alphabetical. If still unavailable, refer to Administrar íconos de aplicaciones.
From the DEVICE section, tap Call.
From the OTHER CALL SETTINGS section, tap CDMA call settings.