I deal with clients almost as often as I deal with internal colleagues. I'll give a more detailed answer in the morning, but for me it comes down to framing my thoughts in an organizational way that makes me as confident as I can be with what I know I'll need to talk about. Edit: a tip that I use when on the phone with clients: I personally find that the more ambiguous the nature of a conversation/meeting is, the more opportunities there are to deviate from what you planned on talking about in the first place. Often times, these surprises worsen our stutters. I make it a point to have a hand written agenda with every topic and sub-topic listed out in detail. I then take a few minutes and familiarize myself with each, asking hypothetical questions to myself to see how I would respond in my head. If there's any hint of confusion or not having an informed response, I flag it to make sure I become comfortable with the material. If it gets to a point that I know I'll be asked multiple questions without having any substance in my answers, I plan on telling them right once we reach that topic that I would rather postpone that discussion. I've found that a misbalance of perceived knowledge in any given subject between two people is something that sparks disfluency.