Fanstel EzPro T56 Handbook
This line-powered phone offers up to 56dB of amplification with no additional AC adapters or batteries required. The EzPro T56 offers 12 volume/tone amplification levels and uses a frequency based approach to amplification, reducing distortion, echoes, and squealing. Large, back-lit buttons with high contrast markings also make it easy to use. This is our simplest amplified phone, with no extra buttons to fool with. Includes a visual ring indicator. One year warranty.
More information: http://www.lssproducts.com/product/8367/corded-amplified-telephones