iPhone 8 will not make or receive calls

Start here: If you can't make or receive calls on your iPhone - Apple Support and contact your carrier for help with this.

The answer given by Apple regarding the network error is wrong. My mobile provider- during an in store appointment today with the General Manager- offered to follow Apple’s suggestions (replace SIM card, etc), but she did not think that could fix the network error on my device (an error that eliminates your ability to make/receive calls and texts). Replacing the Sim didn’t work (expected), and I was told that Apple is no longer willing to do network updates on iPhone 6, 7, and now 8. Because I cannot make/receive calls until I have a network update, and Apple eliminated network updates for the iPhone 8, my phone is now useless. Way to take care of loyal iPhone customers, Apple.