How do I look up on the iPhone which (LTE) cellular band the phone is currently connected to?

GDG, I hear what you are saying...

Those people aren't interested in that feature. There hasn't really been a movement to educate the public about cellular technologies. Instead customers complain why there are signal drop outs, lack of range and "unexplainable" variation in throughput when out and about using their phones. Further, they can't blame the cellular companies who suck them into doing business with them on promises of cutting edge network performance because they can't easily discover that those technologies are not yet installed in their market.

I think that the public would want to know. After all, when it comes to in home wifi, I find that the general public is actually very interested in understanding concepts like wireless B/G/N/AC. And they understand concepts like 2.4 GHz bands vs 5GHz bands. They understand the concept of interference on the 2.4GHz band with pretty much everything else wireless that runs in the house.

I disagree with making the broad generalization that the public wouldn't be interested in cellular frequencies. I do not think everybody will care. But they could care as much as they do about setting up their in home wifi network. I think that the education is just not there in the marketplace right now. Cellular technology is still very technical speak. The wireless telcoms probably don't want the public to know too much as they'd be accountable for missing on the delivery in many places for these great networks they advertise.

Anyhow, hope this is taken as a lighthearted sharing of viewpoints here..

Somebody is doing it. I have seen screen shots of an iPhone being used to display the band on the Internet. There is no explanation for how they are doing it on their site.

Example website with screen shots of the iPhone user interface here: http://www.tmonews.com/2015/10/latest-band-12-lte-sightings-in-florida-californi a-kentucky-and-massachusetts/

What am I looking at a jailbroken phone's UI?

Michael, thanks for the reply. I didn't think I would have to read through the discussion/commentary at the bottom to figure out how this was being done. Typically those comments sections are full of nonsense mixed with relevant information. Thought there might be a faster answer with the apple support community. I have since gone back and read through that and found the instructions the comments section. I see you don't care less about it.

Let me explain why I am looking for this as others might also be interested.

T-Mobile has a new band it is using to deploy LTE bandwidth, which is band 12. iPhone 6s is the first iPhone to have band 12 capabilities in it. Band 12 is supposed to have greater range and ability to punch through buildings than other bands that T-mobile uses (if you believe their claims). I am simply wanting to see whether my phone is communicating with T-mobile's towers using Band 12 or not. Tells me whethe the market I am is really accessing their service or not. Personally, I feel like this is a good reason to want to know this.

If you have the new iPhone 6s, the AT&T version of the phone connects to an LTE band that is specific to AT&T's network called band 30. I believe that this is a new cellular band for AT&T. Depending on the interest in cellular coverages and connectivity, an AT&T customer might be similarly interested in knowing which band their iPhone 6s or 6s+ is connecting to. Just is a truth indicator if you will for where the wireless companies really have their "high end" coverage installed.