How To Determine Which Phone Lines Are Active At Telephone Interface
The terminal blocks might be labeled with the phone numbers that had been assigned to those lines. Do not rely on labels to determine which lines are active as they may be wrong. You will need to exactly determine which terminals blocks are active and which are not. To determine which terminal blocks are active, unplug one of the small phone cords and plug a regular telephone into that jack. If you hear a dial tone, that is an active phone line. Plug the cord back in and then continue checking all the other connections in the same manner. Leave all "Dial Tone" lines plugged in and leave all the silent lines unplugged. You might be living in an apartment complex, so be sure that the lines you are checking are the ones to your apartment.
If all the jacks have dial tone, then connect a regular telephone to the jack that you suspect is the correct line and call one of the other numbers. If the connected phone in your hand rings, then you have the incorrect jack so try another jack. When you can call all the numbers and your telephone doesn't ring, then you have the correct "disconnected" phone line. Leave that jack unplugged.
You have now located and disconnected all the inactive phone lines in your home from the phone company's trunk. Close the door on the network interface box and resecure the bolt.