I think this is a good place for a few of these questions. OP is obviously very frustrated. It is a good opportunity to educate someone on the difference between a stutter and awkward social behaviour. It is a good chance for people who stutter to confront these comments. OP needs to chill out and be patient with his colleagues stutter. He should go to his manager if his colleague is taking up too much of his time. That's really it, I think. Most of the post is about dealing with an awkward person. I have met the fluent versions of this sort of person and it is exhausting. OP seems to be conflating a stuttering with being talked over and pinned in calls for 30 odd minutes. Most people are not like this person. At least not where I live. I think acceptance is key. It has helped me tonnes. I am actually confident and getting control of my stuttering after nearly 40 years of it. I hope one day it works out for you too.