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The secret of a caller ID is the modem it has, a device that converts telephone pulses into digital data and vice versa. When you make a call, your telephone handset transforms data such as your voice and your phone number into electrical signals. These electrical signals travel through a complex network of cables to reach the called telephone. If it has a caller ID – the popular Bina – the device’s modem will transform the frequencies at which these electrical signals were emitted into binary language (sequences of digits “0” and “1”):
• Frequency of 2.2 kHz – Represents “0”
• Frequency of 1.2 kHz – Represents “1”
As each sequence of “0” and “1” can indicate a number – the “5”, for example, is “101” in binary language – it is easy for the bina to point out where the call comes from. One last curiosity: the name Bina is an acronym for the expression “B identifies A”. It indicates that the device is capable of decoding the signals from the caller’s telephone (A) and displaying them on the receiver’s telephone display (B).