crossbar switching การใช้

• This method was also used in North American telephone Multi-frequency and crossbar switching systems.
• Two principles of crossbar switching existed.
• The need for instant communication made SAC the Bell System's first customer for crossbar switching equipment.
• 5XB was originally intended to bring the benefits of crossbar switching to small towns with only a few thousand telephone lines.
• They were used in conjunction with wire spring relays, for example to store digits for sending to other crossbar switching offices.
• At Western Electric he worked on No . 4 toll crossbar switching equipment, used in the first dialing systems for connecting calls automatically without a human long-distance operator.
• Ericsson also developed a fully computerized version of their ARF crossbar exchange called ARE . These used a crossbar switching matrix with a fully computerized control system and provided a wide range of advanced services.
• The majority of class-4 switches in the Bell System during the 1950s and 1960s used crossbar switches, such as the Crossbar Tandem ( XBT ) variant of the Number One Crossbar Switching System, or " 1XB switch ".
• Western Electric experimented as early as 1941 with methods of using mechanically activated reeds to produce two tones for each of the ten digits and by the late 1940s such technology was field-tested in a No . 5 Crossbar switching system in Pennsylvania.
• Crossbar switching quickly spread to the rest of the world, replacing most earlier designs like the Panel systems in larger installations in the U . S . Graduating from entirely electromechanical control on introduction, they were gradually elaborated to have full electronic control and a variety of calling features including short-code and speed-dialing.
• The number in cities with panel and crossbar switching equipment was area code-555-1212, whereas in cities with step-by-step equipment the number was 1-555-1212 ( or 112-555-1212 ) for numbers not local but in the same area code and 1-area code-555-1212 ( or 112-area code-555-1212 ) for numbers in other area codes.