How to Use Field Test Mode in iOS 11 and iPhone X

May 2, 2018 - 16 Comments

iPhone Field Test Mode

Field Test Mode on iPhone allows users to get detailed information on their cellular signal and cellular connection, and has long been a popular alternate method of displaying the cell signal on iPhones as a number instead of the signal bars or dots. Field Test Mode is undeniably for more advanced purposes, but some casual iPhone users found value in it as well in order to find a consistently reliable cellular signal.

But ever since iOS 11 and new iPhone models, Field Test Mode is different from how it used to be, and if you enter Field Test Mode in iOS 11 you will not immediately see the numerical dBm cell signal indicator replacing the bars.

Not to worry, you can continue to see the cellular signal as numbers on iPhone with Field Test Mode in iOS 11, it just works a bit differently than it did before in prior versions of system software.

Read on to learn how to access Field Test Mode in iOS 11.x on any new iPhone, including iPhone X, iPhone 8, iPhone 8 Plus, iPhone 7 Plus, iPhone 7, and others.

How to Use Field Test Mode in iOS 11 to See Number Cell Signal Strength on iPhone

The iPhone must have an active cellular connection to be able to access and use Field Test Mode to measure the signal strength, the rest is easy:

  1. Open the “Phone” app on your iPhone and enter the following number exactly:
  2. *3001#12345#*
    How to enter Field Test Mode on new iPhone models

  3. Press the Call button to dial the number, this will immediately launch the hidden “Field Test Mode” app on the iPhone
  4. Tap on “LTE”
  5. How to enter Field Test Mode on new iPhone models

  6. Tap on “Serving Cell Meas”
  7. How to enter Field Test Mode on new iPhone models

  8. Look for “rsrp0” and the number corresponding will be the numerical measurement of the iPhone cellular signal strength in dBm
  9. Seeing cellular signal strength of reception in dbm number format on iPhone

RSRP stands for Reference Signal Received Power and is a variation of RSSI measurement.

RSRQ stands for Reference Signal Received Quality.

Supposedly rsrp0 is the primary cell tower connected to, and rsrp1 is the next closest cell tower (or one with the strongest connection anyway), each obviously has their own cellular signal strength depending on power, connection, distance, interference, and other measures.

As for the numbers, which are measured in dBm, they will range from -40 to -130, with -40 being the best possible signal and -130 being the worst. Generally speaking, once you start approaching -110 or lower you will find the cell service is spottier and voice conversations may sound garbled or have aspects cutting out, whereas if you’re at -80 or so your signal should be pretty good and not have any issues.

Field Test Mode has a lot of data available, much of which is going to be completely useless or befuddling to the average iPhone user, much less anyone who is not a field test engineer or operator (and I am neither). For the geekier folks who are interested in numerical measurements of their cellular signal, “Serving Cell Meas” and “LTE Neighbor Cell Meas” are likely the two most pertinent sources of information, since both of those will reveal numerical cellular signals akin to what used to be displayed by default in Field Test Mode before iOS 11.

Cellular tower signal strength as seen in iPhone Field Test Mode

Note that accessing the dBm numerical cellular signal details may vary per iPhone model and cellular carrier, with some cellular providers not easily sharing this information through Field Test Mode. The approach above was walked through on an iPhone X with the latest iOS 11.x release on AT&T with an LTE signal, but if you want to view other GSM or UMTS signals then you’d look for the appropriate selection within the Field Test Mode app on iPhone.

And yes, at least at the consumer level, this is the only way to access Field Test Mode on the iPhone, and it has been that way for quite some time.

How do I get the signal numbers to replace the bars on iPhone X, or iOS 11?

Many users want to replace the bar signal indicator with the signal numbers instead, since the numerical reception indicator is more accurate. Unfortunately this is not possible in current versions of iOS or on the newest iPhone models with late iOS software. As of now, only iOS version before iOS 11 can use the numerical reception indicator as a replacement for the cell signal reception bars. If you want to learn how to do that on an earlier device with an older iOS release, go here to do so.

Do you have any other tips or helpful information for iPhone Field Test Mode with the latest iOS releases and newest iPhone models? Share them with us in the comments below.

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Posted by: Paul Horowitz in iPhone, Tips & Tricks


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  1. JayTee says:

    These are not the menus that I see on my Sprint iPhone 8. It appears that the menus you show only apply to GSM model phones and not CDMA phones. I do not get “Main Menu” – I get “Field Test”.

    • Lee says:

      I have the same problem. So I went to UMTS Cell Environment, then Neighbor Cells, then UMTS Set, then O and found a decibel reading. Its the only decibel reading I could find so I figure it’s mine! I live in a rural area and there is only one tower nearby.

  2. joris says:

    same here (5s)

  3. Brent says:

    “Many users want to replace the bar signal indicator with the signal numbers instead, since the numerical reception indicator is more accurate. Unfortunately this is not possible in current versions of iOS 11 or on the newest iPhone models with latest iOS software.” I depended on the signal numbers rather than bars before iOS 11….how many users have to request/complain before Apple brings that option back?? Thanks for considering it ASAP Apple!

  4. Fred Regan says:

    I get the Verizon error message, “We are unable to place your call” I can’t bring up the field test mode. What did I do wrong?

  5. Lexiepex says:

    I had this a few years back, I never found a way to get rid of it and go back to the original bars: even not when updating the iOS to the next level. Or fater a complate reset ! How to do that? before I try this one out?

    • bigtime says:

      Just tap on the signal numbers to change them back to the signal bars on iPhone.

      But as the article says the signal numbers are not visible on iPhone X, etc

      • Lexiepex says:

        I have an SE. GSM not LTE. 11.3.1
        I did not succeed to do the proposed trick: i get the field test mode alright with all the data, but the menuu is very different from what is explained above. No worry, I will not pursue this. Thanks.

  6. william riedhart says:

    On my iPhone SE running IOS 11.3.1 I get the field mode screen but it looks like the old one with 7 items one of which is serving cell measurements which has an RSSI reading which seems to translate to the bars, mine was around -108 and had 2 bars. The display updates until I leave it and go to another screen and when I go back all the numbers are frozen. The only way to get a live display is to power off the phone and power it back on then enter the *3001# number and the numbers update again until I leave that display. So it works once per power cycle.

  7. Darren says:

    How do I see the 3G signal strength. I click on UMTS>Serving Cell Meas and it just says come back later. I do comeback later and it still says the same thing. I have an iPhone 8 Plus on Rogers.

  8. John H Noble Jr says:

    When I follow the instructions here, I get the unending message “Waiting for Update” in black on the left side of my iPhone 8 screen and “Waiting for Update” in blue on the right side. I’ve left my device on this page overnight only to find it stuck in the same place the next day.

    BTW, I called Apple support for help. The lady did an inadequate job, to say the least, when I read to her instructions I had received about accessing the field test mode. She simply denied that iPhones had an field test mode. I ask if she would consult with her supervisor to make sure. She refused on the grounds that she knew all about iPhone capabilities and it would be a waste of her time.

    I’m wondering how to join in any effort to force Apple admit that it is refusing to support the field test mode. Maybe a “shame campaign” moving the issue into widespread public awareness would help.

  9. skoozik says:

    This information is out of date. Take it down. Apple are, for some reason, very interested in their users not being able to access the dB reading. They have changed the procedure so that the reading is not accessible—ie, they’ve purposely gone in and altered the procedure once information began to appear on how to see decibels in ios 11. The procedure described here will no longer work.

  10. 2noc2u says:

    My field test shows the words but has no data. It’s also different from yours. I have ios 11.3. I use to be able to do this but now it doesn’t work. It shows no decibels in the top left corner . Just shows 4 bars. Why is mine so different from others. Serving cell measurements shows no numbers.

    • classic says:

      Here is an article that describes in detail how to use Field Test Mode on new iPhone models with iOS 12 or iOS 11

      It discusses how you can see the decibel indicator of cell reception in number format, and also the bars, and how it is different from earlier iOS versions with Field Test Mode on iPhone.

      It is helpful to read these to learn how to use Field Test Mode on iPhone now.

  11. Matt says:

    It’s funny. Those of us who have been upgrading phones regularly notice issues right away. When I got this last week and fired it up I immediately noticed the WiFi 5GHz was acting funny. I thought maybe it was my network because it flakes every once and while but it’s definitely the phone. My LTE is registered at -103 at home. That’s normal here.

  12. Jim says:

    Verizon iPhone 6s running iOS 11.3.1. I was able to get into the field test mode, but as noted by others the menus are different. Under “Serving Cell Measurements” is has “Measured RSRP” and “Measured RSRQ” as options.

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