Big-Tel 1500 Solo Cordless portable telephone with big keys, 80dB ring and up to 30dB amplified handset volume makes this a great help for any one with hearing difficulty. Variable sound levels. Connect up to 4 more portable handsets with this base. Intercom function. ” In addition to loud ring, there is optical light flash to indicate incoming call. Back lit display screen and back lit illuminated numbers. Memory functions; redial, direct dial and 100 entry phone book. ” Low battery warning. Ring tone choice. Hearing aid compatible.