I recently bought one of these for my mother and we're both very happy with it. It's the Uniden EZI996 900 MHz Cordless Phone for the Visually or Hearing Impaired — a one-line telephone that's perfect for someone who has trouble hearing or reading the buttons. The ringer and the handset volume can be cranked up to high levels and both the base and handset have a light that will flash when the phone rings or when a voicemail message is waiting. The thing has pretty good sound, too. You can read more about it or even order one here.