Vonage Virtual Phone System

Hello!
Has anyone used Vonage as their virtual phone system? Many patrons I speak to over the phone have difficulty hearing me (it cuts in and out). I've tried using the app on my phone, then switched to my laptop. I've tried different headphones (Bose/Apple). I'm directly next to my router, but I've also tried plugging in via ethernet. 
Would love to know your experience if you've worked with Vonage before.
Thanks!
Michelle