Portable communication terminal for remote database query

Abstract

A portable terminal suitable for brief queries to a central database can be employed with any available telephone for communication over the public telephone network. Message characters are entered through the keyboard, stored in memory in digitally coded form, and displayed in a display window. A speaker is acoustically coupled to the telephone mouthpiece. After dial-up connection to a host, a stored message is recalled and transmitted; the stored digitally coded data is converted to a code employing unique sequential pairs of standard DTMF tones, provided by a tone generator to the speaker. The message can be compared off-line, stored, and edited using special function keys including insert and delete. Telephone numbers can be dialed through the terminal keyboard, and are transmitted in standard DTMF coding. Telephone numbers can be stored as messages, or can be embedded in text messages. Host response is transmitted in audio coding (recorded or synthetic speech) to the telephone earpiece, or in DTMF coding to a microphone connected to the earpiece; DTMF coded response data is converted in the terminal to digitally coded form for storage.