I'd suggest putting a tiny blurb at the bottom of a cover letter, possibly saying something to the effect of I am a PWS and not very fluent over the phone, but I would be more than happy to talk to you in person about this wonderful opportunity and blow your damn socks off. The phone is an odd thing. Some PWS have a ton of trouble and some have none. An informal survey suggests it might be because people on the other end can't see you stuttering and so don't know what the dead spaces are from. "What, did you forget your name?" Is my favorite thing to hear on the other end. So many good memories...