Provides interface for 8 digital stations and 2 analog stations Also provides interface for Music on Hold or Background Music source External paging Zone Equipped with 4 8 conductor interface jacks. 2 for 8 digital stations 1 for 2 analog stations or Doorboxes 1 for Music on Hold/Background Music input, and External Paging Zone output, and 2 relay circuit connections. The above relay circuits are available for Door strike control, when analog ports are used for Doorboxes Control for Music on Hold or Background Music source Control of External Paging Equipment Installs only in universal slots 1 3 of Main or Expansion Chassis. Allows addition of 1 3 Port CO Trunk Daughter Board 3COIDB or 1 PRI Daughter Board 1PRDB . Maximum 3 per Main or Expansion Chassis. Maximum 9 per system.