no cellular network

Have you tried removing your SIM card, cleaning the gold contacts with some Isopropyl, drying it with a paper towel, and then putting the SIM back in?  Have you tried completely powering your device off for a minimum of 5 minutes to allow it to refresh on the network?  Have you tried manually selecting the T-Mobile network?  

I'm having the same problems as my neighbor. 'network unavailable. calls going directly to vm, phone doesn't ring for incoming calls, outgoing calls go directly to vm, text messages require 2 or 3 attempts before they can be sent. Network issues!

Rzmer,I'm having the same exact problem as you described, I took my phone to a tmobile store they registered me on the esim card,and took the removable sim card out ,but still having the same problem, and my phone started acting seems like after the last security update ,this is very annoying, I'm missing very important calls,and I'm experiencing dropped calls also very often ,and I always have to restart my phone, this is extremely annoying, paying phone service that barely works, I'm thinking of going to another carrier, I never had this problem under sprint.