Unlocked AT&T LG3 is not Working as a Phone with T-mob Sim Card


Sep 19, 2017
I had LG3 with Tmob and was really happy with it. Recently it stopped working and I bought the same from Amazon unlocked from AT&T. When I put Tmob sim card, it start download all my contacts and apps. I was able to make several calls at the beginning, but later, when all apps were downloaded, I was unable to make calls at all. I wonder why? Everything seems is working good, and Internet too, but not for the calls. What I can do to make it work as a phone too?