Automatic Telephone Answering Machine

An automatic telephone answering machine or system is an electronic device that answers automatically to an incoming telephone call and plays a prerecorded message and is capable of recording a message the caller want to leave. These systems include message recording system having remote acess to message playback, automatic dialing, equipment to receive an alarm, automatic data entry-answering systems and other common telephone devices being used along with modem equipments. The microcontroller typically controls a number of peripherals, components of the answering machine such as an LCD or LED display, an indicator light for recording and playback options, a DTMF receiver and an audio controller. A telephone answering machine must be capble of being remotely activated consisting of: A switch deciding the mode of operation either automatic or normal mode. Provison for receiving the calls automatically when in automatic mode. Provison for recording the message to be deliverd to the incoming user and also to record his mesage Storage for the message Microcontoller to deliver control signal as per the mode of operation Commonly used telephone answering devices comprises of a number of features which allow a user to examine the presence of a call, seize calls, play back recorded voice messages, record an announcement etc. Triggering of a telephone answering machine done by counting the incoming ring signals and when the count surpass a preset number set by the user. The machine is programmed in such a way that if the user does not attain his telephone within a specified time period which is the function of number of ring signals, the call is automaticlly answered and a message is palyed back to the caller as well as asks him to leave a message. KEY WORDS: Answering machine, Answering system, Speech compression, ADPCM, Encoding, Decodin