Call box with keyboard communication

摘要

A keyboard and attached interface for a conventional call box is disclosed. The interface constitutes an interrupt between the cellular telephone handset and cellular transceiver which is activated either by a conventional keypad "On" switch or in conjunction with the telephone hook switch. The TDD keyboard is contained within the call box behind its own discrete door where interference with conventional voice communication cannot occur. Upon opening of the keyboard door, the keyboard activates an interactive display which scrolls status messages to the user informing him of call status upon activation of the keyboard. Switching from voice to keyboard communication is enabled until the answering dispatch center interrogates the call box for identity and necessarily location. Assuming that keyboard communication is selected, necessary communication delay is accepted until communication with a TDD capable dispatcher is established. The keypad is of standard layout and is simply altered for rapid emergency communication including "Yes" and "No" questions typically asked pursuant to a conventional decision tree for rapid screening of the situation attendant the caller. Provision made to customize the interface to the cellular telephone environment include enabling transmission to continue despite line interruptions and providing a switched filter to enhance attached modem transmission. Call termination is dispatch center actuated. There is provided a simple TDD interface which is both a service to the hearing impaired as well as providing superior communication in high noise environments.