WWDC 2023 is coming on June 5 - Here is everything you need to know about the event!
It is the carrier id by the signal bars. It is called the carrier logo. In IOS6 there was a program available for download for windows or Mac that allowed you to change the logo to pretty much whatever you want. You can also create your own logo with Photoshop. This is all possible with out jailbreaking your phone. However with IOS 7 it is no longer possible to change the carrier logo without jailbreaking.
Nobody even even slightly suggested jailbreaking. The whole question that started this topic is if anyone knew how to simply change the logo WITHOUT jailbreaking. No one EVER suggested jailbreaking. Just the opposite.