Would someone please decipher these phone cables?

There are four cables going into the phone box. One of the cables'
blue/dot blue conductors is terminated with a plug and plugged
into a jack. This cable's orange/dot orange conductors is spliced
with the blue/dot blue conductors of the other three cables. There
are more than 9 jacks in the house and all jacks work.

I opened two wall plates and found only one cable in the box.
Thus, these two are not daisy-chained. I assume there is one more
such box somewhere.

What's going on here? Why is orange/dot orange spliced with
blue/dot blue? And how come those three cables still work (can
dial in and out) when they seem not plugged into the phone box?
Thanks.