  DTMF TONE TYPE

  This feature has two choices:  timed tone or continuous tone.  If timed
  tone is selected, each time a DTMF key is pressed, a DTMF tone of a
  specific time will be emitted.  These tone times are determined by TONE ON
  TIME and TONE OFF TIME features in the DTMF Options screen.  If continuous
  tone is selected, the tone will remain on as long as the DTMF key is
  pressed.  The tone will stop as soon as the key is released.
