Included are, e.g., connection units and signal transformers of an incoming message, keyboards for mobile phones, number presentation assistive products, dialling, engaged and ring tone indicators, dialling assistive products, receiver holders and receiver amplifiers.
For other functions, refer:
22 06 Assistive products for hearing
24 18 Assistive products to assist or replace arm function, hand function, finger function or a combination of these functions
24 27 Assistive products for fixation