RJ45 Type Connector With 10 Lines
RJ50

From wikipedia


  The 10P10C connector is commonly referred to as an RJ50 connector,
  although this was never a standard registered jack in the Universal
  Service Order Codes. The 10P10C has 10 contact positions and 10
  contacts.
  
  The most common uses of the 10P10C connector are in proprietary data
  transfer systems,[19] such as the Digiboard[20] and Equinox
  Super-Serial multi-port TIA-232 adapters.[20] 10P10C connectors are
  also used to implement RS-485 interfaces, and for data link
  connections in APC and Eaton uninterruptible power supplies. In the
  latter case, a keyed 10P10C plug with a protrusion on the pin 1 side
  near the back is used.