Yeah phone interviews suck, but you should defo mention your stutter before hand, I find that people are more comfortable with it. Don’t get me wrong, it can still get pretty awkward and no one will ever be 100% comfortable, but at least they know its not because your nervous, you just stutter. If you have a hard block, stop and laugh, maybe make a little joke if you can. People are going to find out you stutter, why not tell them straight away, if they don’t like it, you don’t wanna work for them. It also helps if you smile (even though they cant see you), you don’t want to sound like your getting embarrassed, you should sound happy and excited. You want the job right? Usually when people are embarrassed or uncomfortable its because you are too. Good luck.