This is from personal experience:
In old flats (such as the ones I've lived in), the wire exits from a hole in the wall and goes into a small terminal block on the wall supplied by the telephone company (in my childhood it was called New York Telephone, now it's called Verizon - whatever that means
In the old days it used to be a type 42-A terminal block - a funky looking little 2-inch by 2-inch square of hard plastic with four terminal screws, only two of which were used for a single line private phone.
A square box-like plastic cover would be fitted over this block to protect it. Hence the colloquial term "box" for this type of fitting.
Nowadays, the 42-A block has been supplanted, and is commonly replaced, by a weird looking "Network Interface Box".
Basically this is a "box" with an RJ-11 type socket so you can plug your phone directly into this socket to test for faults (to see if you get dialtone so you know if it's your interior wiring that is at fault or the telco wiring).
I used a big picture here so you can see how it looks. To access the jack, you rotate the spring-loaded cover out of the way.
From this block or socket the subscriber-provided wires may be run to their respective extension sockets.
Other times (such as my case as a child when we only had _one_ phone), this was THE
only phone socket for the entire flat.
When that was the case, if you had a phone with an RJ-11 type plug, you'd just get one of these simpler (read: cheaper) boxes, which is a 42-A block with a cover fitted with a modular jack on the side.
All fixed wiring was surface-mount (stapled to the wall and baseboard trim) and used 2-pair cable (four solid conductors in a jacket).
Bill Addiss and other USA-based electricians, what is phone wiring like in modern-day houses and apartments? I'm only familiar with the old methods in old apartments.
[This message has been edited by SvenNYC (edited 01-09-2004).]