Peter,
Very interesting! Sounds like you have/are doing very well.
I work for a Network services company. Core business is maintenance but we also offer professional services amongst an array of other things too. More LAN/WAN than carrier based though.
I work in the Managed Services team where customers can outsource a little or all of their in house IT responsibilities to us. We use a variety of tools to monitor and manage their networks. It's good because I get to experience a wide range of networking kit and we have labs/demo areas to simulate scenarios if required. I love getting involved with some of the complex faults/requests.
I have never been to the London DC's as our London engineers, due to their location, get those calls. I have visited the new(ish) DC at Newport, Wales as one of our customer has their core located there. Quite impressive and Massive!
Nick