"Leased Line" Technologies

• Traditionally: a permanently connected (or "nailed up") 'phone line and two modems -- in Australia, the ancient DATEL service worked this way. Bit rates up to 72kbps were available. Note that the term "nailed up" has survived to this day to describe any permanently available data circuit. Many businesses use a modern-day equivalent of this technology by taking advantage of Australia's "untimed local call" charging scheme, using a dial-in modem but holding the connection permanently open.
   
  
• DDS was an early (and fiendishly expensive) digital "leased line" service in Australia, with bit rates between 2400 and 48kbps. The original AARNet was based on this service.
   
  
• ISDN-based services. For example, a Telstra ISDN service can dedicate one or more B Channels as a permanently available data link, see later.
   
  
• Frame Relay services.
   
  
• Asynchronous Transfer Mode services.
   
  
• Others: cable-TV based systems(eg Optus@Home, Digital Subscriber lines (DSL), wireless services, and lots more.