Abstract: A portable card reader is designed to be carried in a wallet or purse. In a first embodiment, the card reader has an electromagnetic head that reads information from a magnetic strip of a card. In a second embodiment, information is read from the card by an array of Hall sensors. In both embodiments, the information read from the card is converted to a sequence of electronic bursts of predetermined frequency, preferably in the audible or ultrasound range. The sound signals are output by a speaker to the microphone of a telephone. The signal is then transmitted over the telephone lines to a remote receiver. The receiver then converts the sound bursts into signal pulses which can be read using the computer software of a conventional card reader.