Okay, when I had to answer phones for a job this is what I did - I still stuttered mind you but it helped. I developed a phone voice: a song-song like voice that is almost sickeningly sweet. I learned this from my Mom who was a secretary.. and I said I’d never do a phone voice... well I do now. Do something that makes you forget your on a phones. Lean back in your chair, turn away from the phone’s base, don’t look at the computer screen until you have to. Get a script. I developed a script for answering the phone (thank You for calling the middle of nowhere ABC company! How may I help you?) and the most basic questions I got asked (our store hours are 8-4 Monday through Friday!) and it was all said in a chipper voice but it worked - it felt Like talking to myself and I don’t stutter when talking to myself.