What should I do for my new Huawei Mate 20?
I used Huawei Mate 8 with AT&T sim card last year, it didn't get LTE but only "H+", and now I will change my phone to Huawei Mate 20.
What should I do additionally to make the best use of this phone with AT&T sim card (for example, get LTE speed)? Do I need to go to AT&T store again to adjust something? Or can I just plug in the sim card to my new phone?