[Samsung Galaxy Note 9 Questions & Answers] IT_Architect:
I guarantee it. The only thing you will accomplish trying to beat the Pie upgrade by flashing your carrier's "U" firmware is to wear out your Bixby button. Notice in John's ADB instructions on the first post of this thread:

"2) Software update (with a blue icon) (underlying com.wssyncmldm) I only disabled com.wssyncmldm."

With carrier firmware, there is no blue icon or underlying com.wssyncmldm to disable, which is precisely why you cannot prevent automatic updates with your carrier's "U" firmware, and no it's not hidden, been there, done that. When you try the same command in ADB with carrier firmware it throws:

Error: java.lang.IllegalArgumentException: Unknown package: com.wssyncmldm

Unless you flash some version of Oreo "U1" firmware, you aren't even at square one because "U1" is the only firmware that will give you the blue Software Update app that enables disabling updates.

*You can get a list of all off the packages on your phone by installing Package List by Ben. It will show the friendly name you see in the interface as well as the underlying.

My concern about your situation is when you switch to US Unlocked, chances are good that you will also lose Wi-Fi calling. The carrier firmware you cited is for T-Mobile. If you are also using their service, you have a better chance of making Wi-Fi calling work on U1 firmware than anyone else. At SamMobile, for the SM-N960U1 firmware, which is where you need to be, there are also carrier-branded versions. I decided to try the Verizon one to see if I would get Wi-Fi calling by doing so. I didn't. The only change I was able to find between that and the US UNLOCKED is during boot it displayed the Verizon logo instead of the Samsung logo, so I switched back to US UNLOCKED for when I change SIMs. I will say you want to determine where you want to be early because I also learned that I could not go back to the US UNLOCKED from U1 Verizon and run HOME_CSC to preserve my setup. I had to flash CSC_ and wipe clean to go from U1 Verizon to U1 US UNLOCKED. I'll even take that a step further. Even if you go from your current version of Oreo and to the one PRIOR, "U" or "U1", HOME_CSC will not work.

Now for a glimmer of hope. The ONLY guys I've run across running U1 firmware (I'm only GUESSING they were using US UNLOCKED) and getting Wi-Fi calling that I've found so far are the T-Mobile guys. It was mentioned that T-Mobile uses stock Android yada-yada-yada, and who knows if they know. Even IF you don't have Wi-FI calling after flashing the SM-N960U1 firmware, don't give up just yet. Remember, using the Internet for calling predates smart phones by a lot, and consequently carries with it the requirement of having an address on file for 911 purposes, even though it is laughable for cell phones. When you run the carrier's firmware "U", there is an area where you can turn on VoLTE and Wi-Fi calling. They are both on by default, but Wi-Fi calling will not activate without an address. When you run the "U1" firmware, the screen to enter it is not enabled. HOWEVER, when I ran... (the name of the app escapes me at the moment)... it showed showed that VoLTE and Wi-Fi calling were both on. VoLTE works for me and Wi-Fi calling does not. After you flash, and if Wi-Fi calling doesn't work for you, I'd touch base with your carrier and ask if they can activate it. They may simply need to add an address to turn it on. I will be contacting Verizon to ask them after transferring the SIM from my old phone to my new phone, but the T-Mobile guys are the only ones I've found talking about it working with U1.

:eek:DANGER!. With the carrier firmware "U", the only boot loader version I've seen to date for Oreo or Pie is version 1. That is NOT true for "U1" firmware. On the "Build number" you are about to flash, ensure the 5th character from the right is a 1. If you flash one of the newer "U1" Pie updates that has a version 2 boot loader, you will never again be able to flash any version of Oreo, nor any currently available carrier firmware because they are all currently version 1. You cannot downgrade the boot loader, nor will you ever again be able flash firmware from an earlier boot loader to that phone.