They did for a long time, but they eventually switched to an Eclipse based system. I believe there was a Nokia team in Dallas that built that.

That was Carbide IIRC: https://en.wikipedia.org/wiki/Carbide.c%2B%2B

You could always tell who was using it in the office because their laptop fans would be at full blast.

First it was Visual Studio, second CodeWarrior and then obviously Eclipse (I probably never used the latter, jumped ship a couple of years before the infamous burning platform.) So every 3-5 years they changed the development environment. Can probably also seen as a sign that Symbian development was tedious and not much fun.