I totally understand you man, there's nothing like the intense feeling of shame that comes from having to pass off the phone or resort to writing or something. But suicide really isn't the answer. There's so much to life and stuttering really is quite a trivial barrier. It always feels so much more significant to us as it does to other people. Seriously, every time I've felt a particular frustration with my stutter and shared that, the other people were just genuinely unaware. Pur stutters are hugely amplified in our own heads. I don't believe for a single second that you don't contribute anything to the world other than being a part-time cashier, because that's profoundly untrue. There are people around you who love you and who's lives will be poorer for your absence. There are people you're yet to meet who's lives will be enriched by your meeting. Have you got any hobbies you enjoy? If not, why not? Do you work out? Even just a short home-workout can seriously boost your self confidence and requires minimum investment.