You need to identify which of these wires goes to the outside phone connection (if any). This is an unholy mess that appears to have been done by some unskilled person. Is that a piece of electrical NM cable sliced with wirenuts. Is this really an air plenum. There's serious code issues here.

You know how the 66 block works? each row of pins has three on the left that are all connected together and three on the right. A few of yours have "bridge clips" to connect the left side to the right.

A line tracer, or even a butt set would help, but you can take a regular phone and a unused phone jack to make your own test set. Get some wires with aligator clips and connect one to the red/green wires on the phone jack and then you can try connecting it to the various pairs available. If you get a dial tone, you can call your cell phone or something to figure out which line you've hit.

It's pretty hard to tell from the pictures exactly what you have, other than a mess. Are these 66 blocks in a residence? Whoever connected the wires to them obviously didn't have a punch down tool (designed for this block).

In a 4-wire telephone cable, you typically use the red/green pair for the first line, and then yellow/black pair for the second line. Given that there are 66 blocks, usually you have 25-pair cables attached to those and then the first line is white/blue (a white wire with blue stripes, and a blue wire with white stripes), and the second pair is white/orange.

If possible, I'd start by making a diagram of all the jacks and cables, and which ones connect to where. Most of what I see in the pictures indicate that you're only using a single pair of wires from each cable.

If you come back with a diagram, we may be able to provide more assistance.