Hello all.
I just inherited an old school Samsung Prostar DCS key system to install in our office. I have some questions that you could hopefully help with. This is my first PBX so if any of this sounds crazy please tell me

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It has a T1 card, an SLI card, an 8SLI card, 2 DLI cards, and a ROM-1 card. We have the standard 12 key DCS phones (no LCD).
We have 3 POTS lines from our phone provider. Researching all I could, I believe we need a TRK-B card to support the 3 lines from the phone company right?
The DCS phones then connect to either one of the DLI cards (up to 8 on each card) and they wire via a patch panel using the 25 pair cable run from the card interface.
I haven't looked entirely through the manual, but I'm guessing there's a way to assign the POTS lines and extensions to buttons on the individual phones via the program phone?
I'm really just looking for a general layman's breakdown on what is happening within the key system, it seems like there's just acronyms everywhere and they don't really help me understand. I understand there's inside lines, outside lines, and know they have to talk somehow, but I'm having a hard time determining where the hardware interaction stops and programming takes over. Any help you can give is appreciated.