LG G8 won't call or receive calls after the update to G820UM40a

Hello @Archmainuser, we're happy to help with troubleshooting steps to help resolve your call concerns, and want to help resolve that discrepancy with your device following a software update.

First, it’s important to check the device model number to make sure it’s still supported after the 3G network shutdown. Check out our list of approved devices that will work on the AT&T Network.  Since we shut down the 3G network, there won't be data or voice service for devices that don't have at least have 4G capabilities. This means that while some device features might still work, but, you won't be able to access our network unless you upgrade to a newer device.

• Once you know your device still works, you may need to restart your device or check the VoLTE or LTE status. Go to Settings, then Connection. Choose Mobile networks, then Enhanced LTE services, and select On.
• Don’t see your phone make and model on the list? That means it may not work anymore. You may need to swap or upgrade to a new one.

Keep in mind: AT&T cannot guarantee the capabilities or performance of any individual device that was not purchased directly from AT&T or an authorized retailer of AT&T.

In these instances, you are able to troubleshoot your device after the software update by following these steps:.

• Visit Troubleshoot & Resolve to fix software update issues start by signing into your account and then selecting "Fix an issue" and follow the prompts. 
• After installing the software update, visit Troubleshoot & Resolve to fix any additional trends with your device or services.

Meet us back here with the results if you still have questions. Thank you for contacting AT&T Community Forums. 

Alasani, AT&T Community Specialist 

OK--the phone is on the list of approved devices(see below) & the android 12 update was OTA from ATT. I goto the Mobile Networks sub-menu & there is no option for Enhanced LTE services--just International Data Roaming, Allow 2G service, Access Point Names & Search for AT&T Microcell. In the APN setting, I have ATT Nextgenphone.  I have deleted all information from the phone & reinstalled it from fresh--no change.

• G8 ThinQ (LM-G820UM**, LM-G820QM*)--The phone is a branded ATT LM-G820UM.

Hi There...  I'm going to have a problem....The phone is currently being used with a ATT reseller---Consumer Cellular. I still get the OTA updates. What can I do?

Contact consumer cellular it has nothing to do with AT&T

Well---the OTA was an ATT update....Consumer Cellular tells me it's ATT's problem---All I would like is a link to a ROM that is Android 10 or 11 to get rid of an update that renders my phone useless.

Hello Archmainuser, let's get you pointed in the right direction for support.

As the Ace, @Constructive stated you will need to contact Consumer Cellular at 888.345.5509. They would be able to offer you support for your device not being able to make or receive calls.

Thank you for visiting AT&T Community Forums!

Carlton, AT&T Community Specialist 

I have already contacted Consumer Cellular & they say that as the update came from ATT---the problem is with ATT.....I did remove the Consumer Cellular SIM & put in an ATT SIM & rebooted the phone & everything tried to work (of course, no network was available-old SIM)....I would like to know why.  Have you removed access to the system unless I am only on ATT?