Although I don't know anything about ratings. I can say this about the Cingular 3125. My husband has 30% hearing in 1 ear with his hearing aid in. He is deaf in his other ear. With the Cingular 3125 sold by AT&T; he can hear just fine when he takes out the hearing aid. The aid is so large and he gets feedback if it is left in.
The Hearing Aid Compatibility Act (HAC) of 1988 set the rules for hearing aid compatibility and cell phones. Unfortunately for the hearing impaired no reviewer ever indicates the M or T ratings of cell phones. Apparently it is not important to the reviewers because they're only interested in what the hearing people are interested in. As of this writing AT&T does not have a cell phone with a rating of M or T4. Although I'm not a fan of Verizon, at least they do have more cell phones with the highest rating (M4 or T4) than any other manufacturer. I wonder, at times, how can Verizon and AT&T sell cell phones of the same brand (RAZR) yet one service (Verizon) has the highest hearing impairment compatibility rating.