The wireless telephone industry has developed ratings to assist hearing device users in finding wireless devices that may be compatible with their hearing devices. Not all wireless devices have been rated. Wireless devices that are rated will have the rating displayed on their box together with other relevant approval markings, such as on the website by the displayed phones.
The ratings are not guarantees. Results will vary depending on the user's hearing device and hearing loss. If your hearing device is vulnerable to interference you may not be able to use a rated wireless device successfully.
M-Ratings: Wireless devices rated M3 or M4 meet FCC requirements and are likely to generate less interference to hearing devices than wireless devices that are not labeled. M4 is the better/higher of the two ratings.
T-Ratings: Wireless devices rated T3 or T4 meet FCC requirements and are likely to be more usable with a hearing device's telecoil ("T Switch" or "Telephone Switch") than unrated wireless devices. T4 is the better/higher of the two ratings. (Note that not all hearing devices have telecoils in them).
Most phones that are rated T3 also have an M3 rating. Similarly, most phones rated T4 also have an M4 rating.
Hearing devices may also be measured for immunity to this type of interference. Your hearing device manufacturer or hearing health professional may help you find results for your hearing device. The more immune your hearing aid is, the less likely you are to experience interference noise from wireless devices.