Cicso Independent ClearSounds CSC600 UltraClear White Amplified Phone

My mother has lost all hearing in one ear (great while growing up and coming in late on a weekend, knowing she slept on her good ear). We have struggled to find a phone that worked for her to hear. We get one or two to work but they are still not loud enough in on the handset for her to hear when people are speaking. We are incredibly impressed with the phone and she is so super excited after 20 years to be able to hear phone conversations now. We do not use the speaker due to background noise.