iOS 14 Includes Redesigned Field Test Mode

Apple's upcoming iOS 14 update introduces multiple design changes, including a new look for the hidden Field Test Mode feature on the iPhone.

As noted on the MacRumors forums, Apple has overhauled Field Test Mode to provide more useful information at a glance.

ios14fieldtestmode

Field Test Mode in iOS 14

There's now a Home section with LTE Cell Serving Info, along with a menu section that has other details like device info and breakdowns of LTE, UMTS, and GSM functionality.

Much of the info available in iOS 13 and iOS 14 is the same when it comes to Field Test Mode, so the change is primarily related to design and making it easier to navigate through the hidden app.

Field Test Mode is designed to allow ‌iPhone‌ users to access in-depth information about cellular signal and cellular connection. Field Test Mode is designed for engineers and cellular operators and most people will not need to use it on a regular basis.

ios14fieldtest

Field Test Mode in iOS 14

You can access Field Test Mode on an ‌iPhone‌ by opening up the Phone app, inputting *3001#12345#* and pressing the phone button. It won't make a call, but will instead open the Field Test app.

Field Test Mode was formerly useful because it could turn the cellular signal bars into a numerical measurement, but that is not something that works on modern iPhones with recent versions of iOS.

ios13fieldtest

Field Test Mode in iOS 13

It can still sometimes be useful to see cellular signal represented as a number, and that's still possible on iOS 13 and 14. After entering the Field Test app, tap on LTE (from the main menu on iOS 13 or the menu list on iOS 14) then tap on "Serving Cell Meas."

The measurements that read "rsrp0" and "rspr1" are your cellular signal strength in decibel-milliwatts. These numbers are always negative, and a lower negative number is better than a higher negative number and represents a stronger connection. Numbers range from about -50 to -130. Closer to -50 is a strong signal strength, and when you get to around -100, that's a poor connection that's spotty with slow data speeds if a connection can be made at all.

Update 6/15/21: Apple appears to have updated Field Test Mode and certain metrics like "Serving Cell Meas" appear to be no longer available to access.

Related Forum: iOS 14

Top Rated Comments

Ion-X Avatar
35 months ago
-130 is a lower number than -50, and is more negative, though. Rather than “a lower negative number is better,” it’s more accurate to say “a less negative number is better.”
Score: 15 Votes (Like | Disagree)
ApfelKuchen Avatar
35 months ago

We need a manual for this field test so people can understand exactly what is what!
Yep, because this is a clear case of "a little knowledge is a dangerous thing." It's the kind of info one might see in a professional telecommunications test instrument. It's not a go/no-go test, it's quantitative measurement. Unless you know what every measurement means and how various measurements interrelate, it's nearly useless. But an end-user can latch onto one or two measurements out of the bunch and decide they have a problem.

Radio signal strength/signal quality measurements are particularly tricky, as strength and quality are affected by even small changes in the local receiving environment - moving as little as a few inches or slightly changing the angle of the receiving antenna can make a huge difference.

Consider the comments about whether -130 should be considered "lower" or "less negative." In the case of signal strength, -50 is a stronger signal (better) than -130. However, if we were talking about a noise measurement, -130 would be better than -50. Still, this doesn't tell us whether -130 is good enough.
Score: 7 Votes (Like | Disagree)
Stridr69 Avatar
35 months ago
Too bad that iOS doesn't allow the use of apps like this one. However this can be used as a reference.
For example -101 dBs = RSPO on iOS. The lower the number, the better the signal.
LTE+=CA status IS in use. This particular app dosen't show total Mhz bandwidth in use, unfortunately(like another app that I use shows 3XCA:20x5x5MHZ for a total of 30 MHz
The number 66 on the upper right is the frequency band band in use. Don't see it on the examples given here in this thread. S/B freq_band_ind 66
Fc=Actual frequency used, in this case 2145 Mhz(2.145 Ghz)

Reference only folks, but fun to use...

Attachment Image
Score: 6 Votes (Like | Disagree)
littlepud Avatar
35 months ago

We need a manual for this field test so people can understand exactly what is what!

I find it strange that it doesn't look like iOS at all.
A manual and a nice interface are both completely unnecessary. The labels and meaning for each value are all in the UMTS/HSPA/LTE specifications defined by 3GPP, the standardization body that writes the cellular network specs. Anyone who truly needs to work with the Field Test Mode (i.e. an RF engineer working for a mobile carrier or a cell-site / base-station manufacturer) would already know what to do with all of the output. This is not a feature meant for end-users (like most on the forum here) and is not really useful beyond being a technological curiosity.
Score: 5 Votes (Like | Disagree)
twolf2919 Avatar
35 months ago

Yep, because this is a clear case of "a little knowledge is a dangerous thing."...
Maybe, but it can also be extremely useful - even if you don't know what one or two numbers are about. Case in point:me! We moved to a new house whee my T-Mobile cellular connection showed "No service". But by looking at the field test screens, I saw that there actually was a signal - it's just that the iPhone interprets it so weak as to constitute "No service". Knowing this, I was able to get cellular service by installing an antenna on the roof - again using the field test mode to point it in the best direction - and an indoor amplifier (and indoor antenna). Now I have service. And the only measures in field test mode I used were rsrp0 and another one that measured quality rather than strength but whose name I already forgot again :-)
Score: 4 Votes (Like | Disagree)
ozonenetwork Avatar
30 months ago
anyone know how to restore deleted line ?

Attachment Image
Score: 3 Votes (Like | Disagree)

Popular Stories

iOS 17 on Phone Feature

Gurman: iOS 17 to Provide Several 'Most Requested Features'

Sunday March 26, 2023 6:05 am PDT by
Apple changed the strategy for iOS 17 later in its development process to add several new features, suggesting that the update may be more significant than previously thought, Bloomberg's Mark Gurman reports. In January, Gurman said that iOS 17 could be a less significant update than iPhone updates in previous years due to the company's intense focus on its long-awaited mixed-reality...
iOS 16

iOS 16.4 Will Add These 8 New Features to Your iPhone

Sunday March 26, 2023 8:06 am PDT by
Following nearly six weeks of beta testing, iOS 16.4 is expected to be released to the public as soon as this week. The software update includes a handful of new features and changes for the iPhone 8 and newer. To install an iOS update, open the Settings app on the iPhone, tap General → Software Update, and follow the on-screen instructions. Below, we have recapped eight new features and...
apple mixed reality headset concept by david lewis and marcus kane

Some Apple Employees Seriously Concerned About Mixed-Reality Headset as Announcement Draws Closer

Sunday March 26, 2023 8:25 am PDT by
Some Apple employees are concerned about the usefulness and price point of the company's upcoming mixed-reality headset, The New York Times reports. Apple headset concept by David Lewis and Marcus Kane Initial enthusiasm around the device at the company has apparently become skepticism, according to eight current and former Apple employees speaking to The New York Times. The change of tone...
Steve Jobs Theater dusk

Apple Reportedly Demoed Mixed-Reality Headset to Executives in the Steve Jobs Theater Last Week

Sunday March 26, 2023 5:53 am PDT by
Apple showcased its mixed-reality headset to the company's top 100 executives in the Steve Jobs Theater last week, according to Bloomberg's Mark Gurman. In the latest edition of his "Power On" newsletter, Gurman explained that the "momentous gathering" is a "key milestone" ahead of the headset's public announcement planned for June. The event was intended to rally Apple's top members of...
top stories 25mar2023

Top Stories: iPhone 15 Pro Design Leak, iOS 16.4 Coming Soon, and More

Saturday March 25, 2023 6:00 am PDT by
We're still almost six months away from the official unveiling of the iPhone 15 lineup, but it seems like every day we're learning more about what to expect from the next-generation models. Notably, this week gave us our clearest look yet at what appear to be some changes for the volume and mute control hardware. iOS 16.4 and associated releases are also right around the corner with some new ...
iOS 16

Apple Releases iOS 16.4 With New Emoji, Safari Web Push Notifications, Beta Changes, Voice Isolation for Calls and More

Monday March 27, 2023 10:03 am PDT by
Apple today released iOS 16.4, the fourth major update to the iOS 16 operating system that initially came out last September. iOS 16.4 comes two months after the launch of iOS 16.3, an update that added Security Keys for Apple ID. iOS 16‌.4 and iPadOS 16.4 can be downloaded on eligible iPhones and iPads over-the-air by going to Settings > General > Software Update. It can take a few minutes...
Hero0009

Best Apple Deals of the Week: Samsung's Smart Monitor M8 Gets Massive $250 Discount, Along With Year's Best AirPods Prices

Friday March 24, 2023 10:23 am PDT by
We saw a lot of great deals on Apple products and related accessories this week, including Samsung's iMac-like Smart Monitor M8 for $250 off, a 30 percent off spring sale at Anker, and the year's best prices on numerous AirPods models. All of these deals are still available to purchase right now, so we're recapping them and more below. Note: MacRumors is an affiliate partner with some of these ...
dynamic island

iPhone 15 Dynamic Island to Include New Integrated Proximity Sensor

Friday March 24, 2023 12:27 am PDT by
This year, all iPhone 15 models will include Apple's Dynamic Island that unifies the pill and hole cutouts at the top of the display, but there will also be a material change to the feature that wasn't included in the iPhone 14 Pro models. According to a new tweet by Apple industry analyst Ming-Chi Kuo, the proximity sensor on the iPhone 15 series will be integrated inside the Dynamic Island ...