Doing practice phonecalls

Doing practice phonecalls So I've been doing some practice phonecalls to pharmacies asking for random medicines and if I need prescriptions for them. I try to talk slowly with clear pronounciation and I also try to sneak in a 'stutter' on purpose. For example: 'goo-goo-goodmorning'. Sometimes I get stick for maybe a second but for the most part i'm pretty fluent doing these practice calls. One thing that I noticed was that even though I rarely het stuck during these calls, the receptionist of the pharmacie occasionaly still says. 'can you maybe repeat that, you're breaking up on me.' how fluent do we need to become to stop getting these reactions?