Portable device for enabling a person with serious hearing impairment to use conventional telephone apparatus in the public telephone network

Mobile device for enabling a person with serious hearing impairment to use the public telephone network, where the person with impaired hearing transmits speech signals from his telephone apparatus to the recipient and by means of the device receives character signals from the recipient's telephone apparatus. The recipient is assumed to have a telephone apparatus which can transmit character signals. The device comprises a microphone 2 with amplifier 18. The microphone can be placed on the earphone of the conventional telephone receiver which the person with impaired hearing uses. An optical signal device 19, 20 is connected to the microphone amplifier 18 which device indicates the ringing, reply and engaged signals to the person with impaired hearing. A character signal receiver 21 is also connected to the microphone amplifier 18, arranged to receive character signals from the recipient's telephone apparatus and to generate a binary code which by means of an associated erasable read only memory 23 and associated control circuits 22, 26, 27, 28, 29, 30 are used to convert the received character signals into optically readable characters, letters or numbers, which are presented on a display 24 connected to the read only memory 23.