dead air time on almost every call

Our phones are one week old…90 percent of my calls result in dead air time during the call where the service cuts out. Typically the call isn’t dropped it just goes in and out. We are in an open area of the house and have never had an issue with calls as we are in a metropolitan area. This happens at work, at home, in the car…I need to know a few options. I’ve gone in the store and they rest my network settings, I’ve toggled between airplane mode off then back on, Ive restarted my phone. Please help.