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.

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.

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.

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.

Related Roundups: iOS 14, iPadOS 14

Top Rated Comments

(View all)
Avatar
13 weeks 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: 14 Votes (Like | Disagree)
Avatar
13 weeks 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)
Avatar
13 weeks 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)
Avatar
13 weeks 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...

Score: 5 Votes (Like | Disagree)
Avatar
13 weeks 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)
Avatar
13 weeks ago
Attention to detail!

This is very useful. Thank you Apple.
Score: 3 Votes (Like | Disagree)

Top Stories

New Photos Offer Better Look at iPhone 12 Color Options

Tuesday October 20, 2020 2:34 am PDT by
As we wait for the iPhone 12 review embargo to lift later today, more pictures are circulating of the devices in real-world lighting conditions, providing a better look at the different colors available. Leaker DuanRui has shared images on Twitter of the iPhone 12 in white, black, blue, green, and (PRODUCT)RED. The black and white colors are similar to the iPhone 11 colors, but the other...

iPhone 12 Pro in Graphite and iPhone 12 in Blue Shown Off in Unboxing Videos

Monday October 19, 2020 8:20 am PDT by
While the iPhone 12 Pro does not launch until Friday, we now have an early unboxing video of the device courtesy of Twitter account DuanRui, providing a closer look at the shiny new flat-edge design and sleek Graphite color option. Ben Geskin re-uploaded the unboxing video to YouTube, which we've embedded below: Geskin has also uploaded an unboxing video of the iPhone 12 in Blue: ...

Apple Releases iPadOS and iOS 14.1 With Multiple Bug Fixes Ahead of iPhone 12 Launch

Tuesday October 20, 2020 10:06 am PDT by
Apple today released iOS and iPadOS 14.1, the first major updates to the iOS and iPadOS 14 operating system updates that were released in September. iOS and iPadOS 14.1 come a week after Apple released the golden master versions of the updates to developers. The iOS 14.1 update can be downloaded for free and it is available on all eligible devices over-the-air in the Settings app. To access...

Watch: iPhone 12 and iPhone 12 Pro Unboxing Videos and First Impressions

Tuesday October 20, 2020 6:05 am PDT by
Apple's embargo has lifted for iPhone 12 and iPhone 12 Pro reviews. In addition to our detailed review roundups for each device, we've rounded up over a dozen unboxing videos and first impressions below. iPhone 12 in Blue on left and iPhone 12 Pro in Pacific Blue on right via Engadget Key new features of the iPhone 12 and iPhone 12 Pro include a flat-edge design, 5G support, a much faster A14 ...

Gold Version of iPhone 12 Pro Apparently Has a More Fingerprint Resistant Stainless Steel Frame

Tuesday October 20, 2020 11:56 am PDT by
iPhone 12 Pro reviews hit the web today, and one of the more interesting tidbits came from TechCrunch's Matthew Panzarino, who revealed that the Gold version of the device apparently has a more fingerprint resistant coating applied to the stainless steel frame. From his review:Most of the iPhone 12 Pro finishes still use a physical vapor deposition process for edge coating. But the new gold...

Photographer Austin Mann Tests the iPhone 12 Pro's Camera

Wednesday October 21, 2020 4:14 am PDT by
Travel photographer Austin Mann usually performs an in-depth review of new iPhone models to test their camera performance in real-world scenarios. To test Apple's new iPhone 12 Pro, Mann traveled to Glacier National Park, Montana. Mann focused on some of the biggest camera upgrades with the iPhone 12 Pro, including the upgraded Wide lens, Ultra Wide Night mode, and LiDAR autofocus, across a...

iPhone 12 Pro Max Has Smaller 3,687 mAh Battery According to Regulatory Filing

Tuesday October 20, 2020 8:48 pm PDT by
Apple's new iPhone 12 Pro Max is equipped with a 3,687 mAh battery, which is around 7% less capacity than the 3,969 mAh battery in the iPhone 11 Pro Max, according to a regulatory filing published by TENAA, the Chinese equivalent of the FCC. The regulatory filing, spotted by MacRumors, also lists the iPhone 12 Pro Max with 6GB of RAM as seen in benchmark results last week. Apple has filed ...

5G Drains iPhone 12 Battery 20% Faster Than 4G in Benchmark

Wednesday October 21, 2020 3:17 am PDT by
After the first reviews for the iPhone 12 and iPhone 12 Pro emerged yesterday, a new report by Tom's Guide reveals the extent of battery life reductions when using 5G. The report outlines a test wherein the iPhone surfs the web continuously at 150 nits of screen brightness, launching a new site every 30 seconds until the battery drains. Interestingly, the test was run on an iPhone 12 and...

Hands-On With Apple's iPhone 12 and 12 Pro MagSafe Cases

Tuesday October 20, 2020 1:33 pm PDT by
Apple's iPhone 12 and 12 Pro are launching this Friday, and ahead of that release date, Apple is shipping out various accessories like the MagSafe charger and MagSafe cases. Yesterday we took a look at the MagSafe charger, and today our MagSafe case came in the mail, so we thought we'd take another look at the charger to see how it works with the case and just how strong the case magnets are. S ...

Reliable Leaker Suggests AirTags 'Coming Soon' in Two Different Sizes

Tuesday October 20, 2020 1:53 am PDT by
Apple's rumored AirTags Bluetooth tracking devices could launch imminently and will be available in two size options, based on new tweets from cryptic-but-reliable leaker L0vetodream. In typical enigmatic style, the leaker first tweeted this morning that a "big one" and a "small one" are "coming soon," but withheld what they were referring to. However that was followed an hour later with the ...