Modem sharing device

A modem sharing device (MSD), also commonly known as a line sharing device (LSD), modem sharer, or line sharer, allows multiple devices to share a serial connection. Only multipoint serial protocols such as bisync are supported. Both synchronous and asynchronous datastreams can be used. A common example would have a Tandem as host connected to multiple automatic teller machines often with a modem or Cisco router in-between.