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To use Field Test Mode in iOS 13 & iOS 12 and iPhone 11, XS, XR, X, open Phone, dial *3001#12345#*, and tap Call. iOS 13 commonly places LTE readings under All Metrics or Serving Cell Meas; iOS 12 uses older LTE labels, and carrier profiles can change or hide those menus.
Field Test Mode is a hidden cellular diagnostics interface, not a signal booster. The interface can reveal LTE measurements such as RSRP, cell information, and sometimes RSRQ, RSSI, SINR, or band data. The available fields depend on the phone’s model configuration, carrier, SIM or eSIM, radio state, and installed software.
Key takeaways
- The Field Test Mode code for supported iPhones is
*3001#12345#*, entered in the Phone app keypad and followed by the green call button. - On iOS 13, LTE, All Metrics, and Serving Cell Meas are common routes to LTE readings such as
rsrp0andrsrp1, but carrier and build differences can change the menu. - On iOS 12, look under LTE for Serving Cell Info, Serving Cell Measurements, or a similarly named entry rather than expecting one universal path.
- RSRP measures received LTE reference-signal power in dBm; a value closer to zero is generally stronger, but RSRP alone does not predict download speed.
- Field Test Mode observes cellular conditions; it does not increase signal strength, repair a phone, prove a carrier fault, or replace a controlled speed and call test.
How do you open Field Test Mode on an iPhone?
Open the Phone app, choose Keypad, enter *3001#12345#*, and tap the green call button. The code normally opens the Field Test diagnostic interface instead of placing a normal call. The code and menu behavior can depend on the installed iOS build, carrier profile, SIM or eSIM configuration, and radio state.
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- Temporarily turn off Wi-Fi if you want to inspect the active cellular connection. Disabling Wi-Fi is a practical troubleshooting precaution, not a documented requirement for opening Field Test Mode.
- Open Phone and tap Keypad.
- Type
*3001#12345#*exactly, including both asterisks and the final hash. - Tap the green call button.
- Use the version-specific navigation below to find the serving-cell or LTE measurements.
- Record readings only after allowing the phone to settle, and compare readings taken at the same location under similar conditions.
Apple’s public documentation explains the meaning of the ordinary cellular indicators, but Apple does not publish the dial code as a general consumer repair procedure. The iPhone status-icon guide remains the appropriate reference for the normal status-bar indicators.
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Where are the signal readings in iOS 13?
On iOS 13, open LTE or All Metrics from the main Field Test screen, then look for Serving Cell Meas or a similarly named serving-cell section. When the carrier and build expose the values, rsrp0 and rsrp1 are commonly useful for checking LTE reference-signal power.
The exact iOS 13 screen is not guaranteed. A carrier-specific configuration or point release may rename sections, hide some measurements, show blank values, or provide a reduced list. If Serving Cell Meas is absent, inspect other LTE-related sections rather than assuming that the iPhone lacks LTE. The documented changes to Apple’s Field Test interface help explain why menu layouts should not be treated as a stable public specification.
Where are the signal readings in iOS 12?
On iOS 12, open the older LTE-related menu and look for Serving Cell Info, Serving Cell Measurements, or a comparable entry. iOS 12 does not present exactly the same labels on every iPhone, so follow the LTE and serving-cell wording that appears on the particular carrier configuration.
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The older iOS 12 layout should not be confused with the legacy technique that permanently replaced the status-bar signal bars with a numeric dBm value. Modern iOS versions generally expose cellular numbers inside the diagnostic interface instead. The older Field Test Mode navigation overview provides useful context, but individual menus can differ from the instructions shown there.
What do RSRP, RSRQ, RSSI, and SINR mean?
RSRP means Reference Signal Received Power. RSRP is an LTE radio-signal measurement expressed in dBm. Because dBm readings are negative, a value closer to zero generally represents a stronger received reference signal than a more-negative value.
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| Field | What it generally describes | How to use it cautiously |
|---|---|---|
| RSRP | LTE reference-signal received power, reported in dBm | Compare readings at the same place and time; less-negative usually means stronger |
| RSRQ | A related LTE reference-signal quality measurement | Use it as a quality clue, not as a direct speed prediction |
| RSSI | Received signal strength information | Interpret it in the context of the radio technology and other displayed fields |
| SINR | Signal-and-interference conditions | Useful alongside power readings because interference can affect performance |
| Cell identity or band | The serving cell or radio band in use | Helpful when comparing locations or diagnosing handoff and coverage behavior |
RSRP is not the same as download speed. Throughput also depends on spectrum, congestion, modulation, bandwidth, antenna conditions, carrier configuration, and whether the iPhone is using LTE or another radio mode. Third-party Field Test references commonly use roughly −50 dBm as a strong reading and values near −100 dBm or lower as poor, but those are broad rules of thumb rather than Apple-guaranteed cutoffs. Use the Field Test signal-strength explanation for orientation, not as a universal pass/fail test.
How should you compare Field Test readings?
Compare readings by controlling the conditions rather than treating one displayed number as a complete network test.
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- Stand in the same spot for each measurement, such as beside a window, in the middle of a room, or in a basement.
- Keep the phone’s orientation and position as similar as possible.
- Note the time, carrier, network type, and serving band when the interface exposes them.
- Take more than one reading because cellular conditions can change as the phone communicates with the network.
- Compare indoor and outdoor readings to distinguish a possible building-penetration problem from a generally weak location.
- Confirm practical impact with a controlled speed test, a call test, and—when appropriate—the carrier’s coverage or support tools.
A stronger RSRP reading indoors does not prove that the network is uncongested, and a weak reading does not prove that the iPhone has a damaged antenna. Field Test Mode cannot establish whether a SIM is provisioned correctly, whether the carrier is experiencing congestion, or whether walls and windows are blocking the signal.
Do iPhone 11, XS, XR, and X support Field Test Mode?
The iPhone 11, iPhone XS, iPhone XR, and iPhone X can expose cellular diagnostics when the installed iOS version and carrier configuration permit them, but the model name does not guarantee an identical Field Test menu. Regional model numbers, carrier profiles, SIM or eSIM configuration, and the installed software build can change the available information.
| iPhone model | Relevant cellular capability | What to expect for this guide |
|---|---|---|
| iPhone 11 | LTE, including Gigabit-class LTE with 2×2 MIMO and LAA; no 5G | LTE serving-cell readings may be available in the iOS 13-era interface, subject to carrier and build |
| iPhone XS | LTE, including Gigabit-class LTE with 4×4 MIMO and LAA; no 5G | Use the iOS 12 or iOS 13 menu that matches the installed software |
| iPhone XR | LTE Advanced; supported bands vary by model configuration; no 5G | LTE diagnostics may appear, but labels and fields remain carrier-dependent |
| iPhone X | LTE cellular support; no 5G | It shipped with iOS 11 and may run the relevant older iOS generations depending on the installed build |
Apple’s iPhone 11 technical specifications, iPhone XS technical specifications, iPhone XR technical specifications, and iPhone X technical specifications document model-specific cellular support and regional differences. Those specifications do not promise a particular Field Test screen.
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What should you do if Field Test Mode does not work?
If the code returns an error, stays in the dialer, or opens without useful measurements, work through these checks:
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|---|---|---|
| The code does nothing | Re-enter *3001#12345#* exactly, restart the Phone app, and try again |
A typing error or temporary Phone-app state may be responsible |
| The menu opens but LTE is missing | Check every LTE-related section and try with Wi-Fi disabled | The carrier profile or iOS build may omit or rename the section; the phone may still support LTE |
| Values are blank or zero | Wait briefly, move to a location with cellular service, and repeat the observation | The reading may be unavailable or stale; do not treat it as proof of hardware failure |
| Readings look inconsistent | Repeat at the same location and compare with a call or speed test | Radio conditions can change; Field Test Mode is not a complete network-quality test |
| Signal is weak indoors | Compare indoor and outdoor readings and check carrier coverage information | A building-penetration issue is possible, but congestion or absent outside service remains possible |
Use the ordinary status bar as a quick consumer-facing check: Apple says the number of cellular bars indicates cellular-service signal strength, while labels such as LTE identify the available network type. Field Test Mode provides additional diagnostic context, not a more authoritative answer to every connectivity problem.
Can a signal booster fix a weak Field Test reading?
A cell phone signal booster can be an optional solution when outdoor cellular service is usable but a building significantly weakens indoor coverage. A booster cannot create service where there is no usable outside signal, and a booster will not necessarily solve carrier congestion, a provisioning problem, or a network outage.
After comparing outdoor and indoor readings, readers with a small home office or apartment may research a product such as weBoost Home Studio as an example of hardware marketed for weak indoor cellular coverage. A larger residence may instead investigate weBoost Home Complete. Compatibility with the carrier, local regulatory requirements, installation conditions, and usable outside signal must be checked before purchase; neither product should be treated as a universal recommendation. Manufacturer specifications are available in the weBoost product catalog and the Home Complete specification sheet.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How do you exit Field Test Mode safely?
Return to the Home screen or use the normal navigation controls to leave Field Test Mode. Field Test Mode is intended here for observing cellular information. Do not change unfamiliar engineering values or radio-configuration settings, because the interface is not a repair or performance-boosting tool.
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Frequently Asked Questions
What is the Field Test Mode code for iPhone?
Enter *3001#12345#* in the Phone app’s keypad and tap the green call button. The code normally opens Field Test Mode instead of placing an ordinary call, although the result can vary with the carrier profile, SIM or eSIM configuration, and iOS build.
Where can I find LTE signal strength in iOS 12 or iOS 13 Field Test Mode?
On iOS 13, open LTE or All Metrics and look for Serving Cell Meas. On iOS 12, look under LTE for Serving Cell Info, Serving Cell Measurements, or a similarly named entry; labels are not identical on every iPhone.
Is a higher or lower dBm number better in iPhone Field Test Mode?
A less-negative RSRP value is generally stronger than a more-negative value because RSRP is expressed in negative dBm. RSRP alone does not determine download speed, which also depends on congestion, bandwidth, spectrum, interference, and other network conditions.
Does iPhone Field Test Mode improve cellular signal?
No. Field Test Mode only displays cellular diagnostic information. It does not increase signal strength, repair a phone, prove that a carrier is at fault, or guarantee that a cellular booster will improve service.
The Bottom Line
Use *3001#12345#* to open Field Test Mode, then follow the LTE and serving-cell labels available on the particular iOS 12 or iOS 13 build. Treat RSRP and related values as clues, compare readings under controlled conditions, and confirm real-world impact with calls, speed tests, and carrier support rather than relying on one dBm number.
