I work in at the NOC (network operations centre) for the local telco, we service our own territory and a few partner ones as well as managed service customers' servers and network gear. We deal a lot with DMS100, DMS200, DMS10 etc telephony switches. We monitor pretty much everything from the switches themselves, fiber transport, environmental conditions of COs, etc.... Things like if there is an extended power outage somewhere, we track it, monitor battery voltages, coordinate generator deployments if the outage is too long, etc. We also get lot of oddball stuff sometimes to deal with. Basically anything that other departments don't do, comes to us. It can sometimes be interesting, but also sometimes frustrating, especially after 5 when you're the 12 hour day shift guy as all the weird stuff seems to happen then. If we don't know something, we have to know who to call, and go from there.
It's kinda like the fire department. You're pretty much sitting and waiting for something to happen, but when it does, it can be chaos. I love the job, especially because of the shift work. I get lot of time off. For example, I've been off for 6 days, but other times I might work for 4-6 days in a row, 12 hour shifts. So it's balanced. But having all those days off is worth it imo. I prefer nights so I usually ask to get like 6 nights in a row then I get lot of time off.
Our office is in the "hub" regional CO so it's an extremely important building. Security is pretty high and it has a pretty high end fire alarm system. It's also manned 24/7 even on holidays. You actually CAN break the Internet in this building.
This is a completely random site I found that has some of the stuff we work with:
http://www.e-c-group.com/~lindsey/beast/04.html