When I began my sales career which involved a lot of telemarketing and phone work, I still had the odd block creep up. The nice thing about phone work however is that you can generally take a few extra seconds to compose your sentence/work around the word or syllable that's giving you the block. Would having a script to read make things easier or more difficult? You also have a little more leeway with how you choose to pronounce things. For example, maybe switch out the N in "national" for an M ("Mational") if that avoids your block during your conversation. This obviously doesn't work as well when in front of somebody. And I would try to avoid having to resort to tricks like that since you're essentially training yourself to avoid your stutter instead of working on improving it. If nerves and anxiety are what tend to cause you to stutter more, that will wear away as you get more comfortable in your role. I definitely had some challenges when I began and every now and again I hit a block that I could not overcome for the life of me and either had to struggle through an awkward stutter until it got out or find a clever alternative to what I was saying that didn't involve the offending block. And I can't say that there was really any one trick that seemed to help, other than steadily increasing my confidence with success. Rhythmically tapping my knee in time with what I was preparing to say sometimes seemed to help, but you probably already know what little tricks and workarounds tend to help you with your own stutter, especially when nobody is necessarily paying attention to your body language. If you have any specific questions I would be happy to answer them and try to help.