[Samsung Galaxy Note 9 Questions & Answers] IT_Architect:
1. Yes

2. The U vs. U1 is not indicative of a lock vs. no lock. U phones can be unlocked or locked. The U firmware is wireless-provider-specific firmware. It could be Verizon, T-Mobile, AT&T, etc. Each have their own firmware to work with their specific networks. They will also force updates on you whether you want them or not. The U1 firmware is standards-compliant support. The better the wireless provider supports the standards, the better U1 works. T-Mobile supports it perfectly but has some loss of functionality with allied vendors. You may never notice. Next, is Verizon. Verizon was CDMA, so its 3rd gen stuff won't work like the GSM networks will because they don't have any anymore. However, all of the 4G will, and Verizon has more 4G coverage than any of the others have 2+3+4G coverage. Thus, you don't miss the 3G like you would AT&T who is 25%-30% less than 4G, but AT&T has always been GSM so coverage-wise it is close to Verizon. For standards compliance for U1, AT&T is dead last by far, and if that isn't enough, the most resistant to accept a phone not sold by them. If you do not buy a new phone through a wireless provider, it will be a U1 phone. With a U1 phone you can prevent it from updating if you hold your mouth right. You cannot stop a U phone from updating. Other countries were behind the US so they tend to be more standards-compliant because they weren't as heavily in the game when the innovation was taking place. That means for traveling and swapping SIMs for different foreign carriers, you would want the U1. The Note 9 is the first Note with about every band known to man like the iPhone.

3. Yes

4. If the phone was purchased as a U1, it is undoubtedly unlocked because the seller is not selling it on a contract, and has no idea which network the phone will be used on.

Everything I've read, the 960U /U1 are the same hardware. To support that, their firmware modules are the same except one that is carrier-specific. The U1 for the Note 9 is not carrier specific. I had a T-Mobile Note 9 that I used on the Verizon network with no issues. I have a Verizon Note 9 now, and there is no difference. The only reason I have the Verizon Note 9 now is because the brand new T-Mobile one, still sealed in the box and with the protective film on it, ended up on the bad MEID list. Apparently someone bought it and brought it back without using it and stopped paying on it and thought they were out of the contract by doing so. The Verizon U phone that I have now has been flashed to U1 and works fine on their network. So the advantage of the U is its supports all of your carrier's services. The U1 supports all of your carrier's services that are standards-based and don't use carrier-specific services. Example, if the carrier supports support VoLTE, U1 will not usually support it because it must coordinate with the carrier's servers while U will. They say the U1 doesn't have the carrier bloatware. I don't agree. The carrier-specific added services are designed to work with their servers. Moreover, in the areas that need to be filled in, you get the basic programs from Samsung to replace the more capable ones you get from the carrier. I use U1 because I need to stop them from updating me due to my line-of-business software on my phone and for International travel when I replace the SIM with a local network SIM. If that's not you, and you want the latest for your carrier, U is what you want.