I am new to this phone system. It has multiple boards - d line cards a station card, and 2 other cards that Im not sure what they are. Supposedly the system had 12 lines and extensions working before someone moved it to a new building. I can only get 8 lines and extensions working. Plugging into any other card does not work. Also need to know where the music on hold should plug into.. Boards MH5929 (2), DX2NA 4ATRU-3, DX2NA 8DSTU-s. Does anyone have a manual for this system? or Boards? Please advise, I can send contact info.

Thanks