Answering machine

Telephone answering machines perform the basic function that they automatically answer calls incoming on a telephone line if it is not answered first, play a prerecorded outgoing message to the calling party, and then record any message the calling party leaves. Telephone answering machines are now commonly in use and include a number of features which allow a user to screen calls, intercept calls, play back recorded messages, record an announcement, among others. A digital answering machine is used to answer a telephone and store voice messages in an internal memory. The use of an internal digital memory eliminates the need for the magnetic tape cassette that was commonly used in earlier answering machines. Digital memory storage, namely random access memory (RAM), requires the conversion of an analog voice signal generated by a microphone or phone line into a digital representation. For storing digital data in memory, the analog speech signal is digitized at a predetermined sampling rate in a first step. The resultant data stream is compressed in a second step with the aid of a data or speech compression process. The data stream reduced by the data compression is then recorded in a third step in a digital memory. A telephone answering machine is usually triggered by incoming ring signals when the number of ring signals exceed a predetermined number set by the user or manufacturer of the machine. When it is initiated, an out-going message which comprises greetings and recording instructions prepared by a user will be played to the caller and then incoming messages from the caller will be recorded. There are many other additional features which are available. Some devices allow messages to be played back over the telephone network via remote command from the caller.