Active DSP message-board

This project comes from the inconvenience of the traditional message-board for a visitor when the host is not at home. Besides the written message, a visitor can also leave a voice message, can telephone his host immediately, and also include a simple security checking in our board system. When the visitor pushes a special key, the telephone system autodials the preset telephone number by the host. To reduce the system cost, the compressed voice message is stored in the internal and external memory space of the DSP chip instead of the voice IC.