Abstract: A system for enabling securities information to be elicited and transactions to be automatically executed by an investor from a conventional telephone. A portable pocketsized data terminal having a keyboard, a display and status indicator lamps includes an acoustic coupler device for removable attachment to a telephone handset. A centralized computer receives information signals originating with the portable data terminal and specifying information or transaction execution requests, and transmits appropriate responses to the portable data terminal for display. Several levels of security are provided in the system.