Knowing how strong your cell phone signal is can make a big difference when choosing and setting up a signal booster.
Relying on the bars shown on your phone? Not the best idea.
The number of bars can change from device to device, and they don’t give you the full picture. The most accurate way to measure your signal strength is by using Field Test Mode.
What is Field Test Mode?
Field Test Mode is a hidden feature on most smartphones that gives you all the details about your mobile network—things like signal strength, signal quality, and even which frequency bands are in use. It’s a tool usually used by technicians, but you can use it too. The best part? You don’t need any special apps or tools—just your phone!
Field Test Mode is much more accurate than signal bars or speed test apps because it gives you real-time data that shows exactly how strong your signal is and how clear it comes through. It’s a great tool for anyone looking to improve their cell signal.
Why Use Field Test Mode?
Field Test Mode provides three key numbers you’ll want to know:
- Signal Strength (RSRP): This tells you how strong the signal is when it hits your phone. It’s measured in dBm (decibel milliwatts). The numbers usually range from -50 dBm (excellent) to -120 dBm (very weak). The closer your number is to zero, the better your signal.
- RSRQ (Reference Signal Received Quality): This tells you how clean or clear the signal is. It's measured in dB (decibels). The range is usually between 0 and -20 dB. The closer to zero, the better the quality of the signal.
- SINR (Signal-to-Interference & Noise Ratio): This shows how much interference or noise is affecting your signal. Higher numbers are better. Anything above 20 dB is great.
These numbers give you a better idea of how strong your signal is and whether there’s too much interference. If your signal strength is weak, you’ll need a more powerful signal booster. If your signal quality is poor, a directional antenna can help cut through the interference.
How to Access Field Test Mode on iPhone
Accessing Field Test Mode on iPhones can vary depending on your iPhone model and iOS version. It might not work on every device, especially newer 5G models, but it’s worth trying out.
iOS 16 and Above:
Version 1:
- Turn off WiFi.
- Open the Phone app and dial *3001#12345#*.
- Tap RsrpRsrqSinr to see signal strength (RSRP) and quality (RSRQ and SINR).
Version 2:
- Turn off WiFi.
- Dial *3001#12345#* in the Phone app.
- Tap Nr Reach Attempt for 5G signal or Reach Attempt under LTE for 4G signal (RSRP will be visible, but RSRQ and SINR might not be available).
iOS 15 and Below:
- Turn off WiFi.
- Open the Phone app and dial *3001#12345#*.
- Tap Serving Cell Meas to view signal strength (RSRP) and quality (RSRQ and SINR).
For older iPhones (iOS 11 or earlier), you may see RSRP appear in the notification bar after dialing the code.
Important Notes for iPhone Users:
- On iPhones with iOS 16 and above, Field Test Mode might not show all the detailed signal quality metrics, especially for 5G.
- If you can’t get RSRP or SINR readings, you can use a speed test app like Speedtest by Ookla to get an idea of your network performance.
How to Access Field Test Mode on Android
Getting into Field Test Mode on Android devices is a bit simpler, but it still varies depending on your phone’s model and Android version.
Common Methods for Accessing Field Test Mode on Android:
Option 1:
- Turn off WiFi.
- Go to Settings > About Phone > SIM Status.
- Look for Signal Strength, which will show you your RSRP.
Option 2:
- Turn off WiFi.
- Go to Settings > More Options or Mobile Networks > About Phone.
- Find your signal strength (RSRP) under Signal Strength.
Option 3:
- Turn off WiFi.
- Dial *#*#4636#*#* in the Phone app.
- Select Phone Information to see signal strength in dBm.
Note for Android Users:
- While Android devices easily show RSRP (signal strength), they may not show RSRQ or SINR. To get those, you can download apps like Network Cell Info Lite or LTE Discovery to get more detailed data.
How to Use Field Test Mode
Once you’ve got Field Test Mode open on your phone, you'll want to perform a site survey. Here’s an overview of how to do that.
- Walk around your property: Take measurements inside and outside to find where the signal is strongest and weakest. Signal readings update every few seconds, so take your time. Write down the signal strength (RSRP) and quality (SINR/RSRQ).
-
Focus on key areas: Test places like:
- Each side of your building (north, south, east, and west).
- Any upstairs balconies or rooftops.
- Rooms where you use your phone the most.
- Take multiple readings: It’s best to take several readings in each location and average them out. This will help you find the best spot for an outdoor antenna if you’re setting up a signal booster.
Understanding Your Signal Readings
| Metric | Good | Average | Poor | Very Poor |
|---|---|---|---|---|
| RSRP | ≥ -89 dBm | -90 to -99 dBm | -100 to -109 dBm | ≤ -110 dBm |
| RSRQ | ≥ -10 dB | -11 to -15 dB | -16 to -20 dB | ≤ -21 dB |
| SINR | ≥ 20 dB | 13 to 19 dB | 1 to 12 dB | ≤ 0 dB |
RSRP (Signal Strength): The closer to 0, the stronger the signal. Anything above -90 dBm is good, while anything below -110 dBm may cause problems with calls and data speeds.
RSRQ (Signal Quality): This value shows the signal quality and interference. The closer to zero, the better.
SINR (Signal-to-Interference & Noise Ratio): Higher numbers mean better signal quality. Anything above 20 dB is considered excellent.
What If Field Test Mode Doesn’t Work?
If Field Test Mode doesn’t work on your phone, here are a couple of alternatives:
- Borrow an Android phone: Android devices usually have more reliable and accessible Field Test Modes. If you can borrow a friend’s phone, you’ll be able to get accurate readings.
- Use a speed test app: If you can’t get detailed signal readings, try using apps like Speedtest by Ookla or OpenSignal to measure your network performance.
Does Field Test Mode Measure All Carriers?
Field Test Mode only shows the signal readings for the carrier tied to your active SIM card. If you need to check multiple carriers, you’ll need a device with a SIM card for each one.
How to Improve Your Signal After Testing
Once you’ve collected your signal readings, you’ll be able to make a better decision about how to improve your signal. The most effective solution is to use a cell phone signal booster. By placing an outdoor antenna in the area with the strongest signal, you can boost the signal inside your home or office for better coverage.
Conclusion
Using Field Test Mode gives you accurate, real-time info about your signal strength and quality. With this information, you can decide if you need a signal booster and figure out which one will work best for your space.