My guess - the 25-pair with the Amphenol end comes from the demark. Dial tone is on the Wht/Blu and Orn. Because the GC doesn't know how to punch down a 25-pair, he gets a pre-made cable and plugs it into the RJ-21 block. It's the Verizon flavor, with the wire wrap on the back, like Hal notes. But now, dial tone is coming in from the RIGHT, and out on the LEFT, backwards from the way it's supposed to be (amphenol is supposed to be for the CUSTOMER, not the telco.)
Finally, the 4 pair IS from the fire alarm, with Blu and Grn feeding the Primary and Secondary, and Orange and Brown being the returns.
Nice work, NOT!
