"unlocked" Sprint S10+ question

The S10+ in the United States is the same model for every carrier. Once one of those is truly unlocked, entering another carrier's sim card usually forces the device to pull from the sim card and change things (like the boot splash screen) to that sim's carrier. If you're seeing that message, then it likely isn't truly unlocked, or there's something in Sprint's system hanging it up. I don't think flashing Verizon firmware will make any difference as the message you're receiving is tied to the IMEI and sim card more than anything else.

Thanks for the reply! Sounds right! I remember I had an S9+ a couple years ago (that was also Sprint & unlocked), but it got signal and immediately pushed an update that "re-branded" it sort of with a Verizon splash screen and signal icons and such. So possibly not truly unlocked. Thanks for the input!

The S10 may have the same hardware across carriers, but there are certain programmable features that cannot be changed after it leaves the factory. Investigate CSC codes for the phone you are looking at.

I had serious issues with a relashed Sprint phone to Tmobile.

The sprint phone was unlocked, and reflashed, but due to the baseboard still saying it was coded as a sprint it corrupted the workings of the radio components.

Android and all apps worked fine, but the baseboard backgound stuff was confused as which model it should act like.

-Just sayin, you are correct the hardware is the same, but with the functionality of embedded firmware may change if it is a "reflashed" phone.

It's definitely not unlocked, if you're getting those messages.

What's the Baseband Version on the device? You can find that under Settings-->About-->Software Information

Forgot to add: no amount of firmware flashing will SIM unlock it. SIM unlocking goes much deeper than firmware level