When I was trying to make a call, through contacts, on my smart phone I was constantly getting this message "Mobile network not available for voice calls" So when I got home I called Motorola customer service. They advised me to go to Network Type under settings in the phone. There I saw circle LTE , which was recommended and checked off. I was advised to switch to 3G and lo and behold I could make a call . Could someone who knows what this means explain it to me because I haven't a clue. I am just glad that the phone is working now. p.s. this is the moto e4 by Lenovo mobile phone.