Cat3 from Verizon ONT to Old Bell Atlantic Panel
When Verizon (which is the latest iteration of C&amp;P Telephone -&gt; Bell Atlantic) puts in FIOS, they convert the phone lines to run on the fiber from the central office and they come out of the ONT as copper which they then connect to the original Network Interface (a.k.a. DMARC). (&quot;Network&quot; refers to &quot;telephone network&quot;, not to Ethernet.) That network interface will have wires going to the rest of the house and also often still have wires going back out to the street. At some point (typically in or very close to the network interface, they will disconnect the old lines in order to avoid problems.
Each phone line users 2 wires (the RJ11 jacks can handle 4 wires = 2 phone lines). You actually have space for 6 (possibly 12, not clear if that is 6 repeated left &amp; right or 12 separate lines), but currently you only have 1 line connected on the blue/white pair. Blue/white is one of the standard colors within a 4-pair cable, but is also standard for &quot;cross connect&quot; wires, which is the actual function here.
Do you have any traditional &quot;land lines&quot;? Do you want to have any &quot;land lines&quot;? Or are you in cell phone and/or VOIP mode? If you have no need for regular land lines (aka POTS) then you can ignore the old network interface. If you do want regular land lines then there are a number of different ways of wiring them, some of which will make use of that network interface, but not all.