For the last month I can’t make calls when I am away from my WIFI. Is this problem with cell connections or is maybe a problem with Moto Z phone?
There are no known outtages in cellular service.
I would recommend going through the troubleshooting steps in this document
Please try the following steps to resolve this issue:
Reboot the phone in an area that has a strong cell signal. (Some people have simply needed to step outside and reboot.) If this fixes it, stop.
Please ensure the data is turned on in Android Settings. Settings > Data Usage > Cellular Data (some phones may say Mobile Data). If this fixes it, stop.
This one is more complicated. This step will clear out any saved connections for Wi-Fi and Bluetooth that you may have already made. We’re going to reset the network settings.
Go to Settings > Backup and Reset > Network settings reset
Read the warning, tap “Reset settings.” You will be warned a second time. Tap “Reset settings” to confirm. The process will usually take 5-10 seconds and the cellular signal bars icon will go away for a moment. Once the cell signal bars icon returns, you should reboot the phone.