Situational stuttering???

Situational stuttering??? Does anyone else kind of pretty much not stutter (aside from a few words/names that trigger it but pretty much fluent) when calm. As in can hold a conversation saying everything I want to say without much difficulty. But when nervous, as in speaking in front of a class/group of people or answering questions in class feel unable to get the words out? And also on the phone? I'd be speaking to friends and family sounding pretty much fluent but as soon as I need to speak to a stranger (customer service/bank etc) it gets so tricky and I just wanna hang up lol