Hey man, I too work in the IT Support /Service management side It is difficult especially when having to use the phones but honestly doing that in itself has helped my confidence and has desensitized myself to speaking situations. Also, working in a field like ours, we work with a lot of people and that too helps with confidence. I have a video about my experience with a stutter and my career if you also want to check it out. https://youtu.be/_JVgACJGFK4 All the best!