That is odd; Thank you for bringing this concern to our attention. As Mr.Bimmer mentioned. I definitely recommend checking if our phone is in Airplane Mode. But since you are able to make WiFi phone calls, it sounds like that is not causing this symptom. We have a several troubleshooting steps that should help figure out why you are unable to make phone calls using mobile data. Check out the link here for assistance: http://www.samsung.com/us/support/troubleshooting/TSG01001613/
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