I'm sorry to learn that you are also not receiving your voicemail notifications on your Motorola Moto Z3 device. I understand the importance of being able to receive your calls and important messages at all times. Allow me to help.
How long have you been experiencing this problem, and have you noticed this happening when you're at a specific location or in a particular building? Are you also experiencing problems making or receiving calls, texts or making data connections on your device as well?