The communication data transfer rate is measured in bits per second (bps) or band, depending on their transmission speed. Communication channels (paths) are grouped into three basic categories: narrowband, voiceband and broadband.
Narrowband: When the data transfer rate is between 45 to 300 bps then this is called Narrowband transmission. They are used mainly for telegraph lines and low-speed terminals.
Voiceband: Voiceband channels handle moderate data volumes and can transmit data at speed up to 9600 bps. They are so-called because their major application is for ordinary telephone voice communication. Most remote terminals are connected to computers through voiceband channels.
Broadband: Broadband or wideband channels are used when a large volume of data is to be transmitted at high speed. These systems provide data transmission rates of 1 million (106) bps or more. Nowadays, broadband communication is gaining popularity. This is basically used in mobile devices such as cellular phone, laptop, notebook etc.
