In message , AK
writes:
Just curious.

Frontier has a building close to me that is used for the plain old
telephone system.

I was wondering what is in that building and what is it called?

It has no windows.

In the UK, it's generally known as the "telephone exchange"; it is
what's at the other end of the wires that come into your home. All the
connection equipment, the bits that separate your telephone from your
broadband (assuming you get that through your 'phone line), the
switching equipment, the concentrating equipment, the batteries that
keep it going during power cuts, and so on.

I found this.

https://electronics.howstuffworks.com/telephone2.htm

Andy
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

[What's your guilty pleasure?] Why should you feel guilty about pleasure? -
Michel Roux Jr in Radio Times 2-8 February 2013