GreatCall Jitterbug5 User Manual page 191

added together to indicate how usable they are together. For example, if a
hearing aid meets the M2 level rating and the wireless mobile device meets the
M3 level rating, the sum of the two values equals M5.
Under the standard, this should provide the hearing aid user with normal use
while using the hearing aid with the particular wireless mobile device. A sum of 6
or more would indicate excellent performance.
However, these are not guarantees that all users will be satisfied. T ratings work
similarly.
M3 + M2 = 5
T3 + T2 = 5
182 Health and Safety