Hello:

Moved into a house, and just found out that about half of the
phone jacks in the various rooms don't seem to work.

Realize that a probable answer is that the former owner
may have had two lines for the house.
We only have a single one.

I imagine that it shouldn't be too hard to have all the phone
jacks be in parallel, and operable for the one line we do have.

But not sure of the best way to implement this.

Do I do it at the Verizon phone box on the outside wall of the house ?
How exactly ?
Is this "legal" (the opening of this box, and modifying connections inside)
?

Or, do I have to do it inside the hose, trying to find the wires, and
splicing them (all) together, somehow ?

Any thoughts and details on this would be appreciated.

BTW: is it the red and green wires that are used these days for the basic
phone connection ?
what's the yellow wire for ?

Thank you,
Bob