Most people use the signal bars as a visual representation of signal strength. But actually, the number of signal bars is the not the best measurement of the signal strength your cell phone is receiving. You may not be able to make a call when you have 3 or more bars on your phone but sometimes you can even though you only have one. Why?

Because the measurement method is subjective and not accurate. The bar number will fluctuate on phones by different carriers and manufacturers. When you place two phones of different cellular services or different bands, you may get different bars on two different phones.

Learning how to measure signal strength and conduct a signal test is necessary if you’re about to purchase or install a signal booster. Let’s get an understanding.

How to read signal strength?

Using decibel milliwatts or dBm to measure cell phone signal strength is more helpful and accurate. dBm is the standard unit of measure to define signal strength in wire and cables at radio and audio frequencies.

dBm is expressed as a negative number on a signal meter, for example, -65 dBm. The closer to 0 the number reading is, the stronger the signal strength. Signal strengths generally range from -30 to -110 dBm. Generally, -50 dBm is considered to be excellent in signal strength level. Anything worse than -110 dBm is thought to be no signal or dead zone, and you’re unlikely to have cell service. In the case, installing a signal booster is not going to help as the equipment is used to boost the signal rather than create one. To use cell service on your phone, you’re supposed to have signal strength better than -85 dBm. If the signal at your place is not hitting this benchmark, you will need to get a signal amplifier.

How to check the signal strength on iPhone

iPhone Field Test Mode

By accessing the iPhone field test mode, you can measure the signal strength at your building in dBm. Below are some instructions.

  1. Go to setting and turn off Wi-Fi
  2. Dial and call *3001#12345#* to enter the field test mode
  3. Tap Serving Cell Measurements
  4. Scroll down to Measured RSSI

Note: This is for iPhone using iOS 11. For other iOS versions, it may vary.

Check with A Specialized App

Beside iPhone field test mode, there are some helpful specialized apps that users can download and test their signal strength.

These apps are free and can be downloaded from Google Play or Apple Store. These works with Android system as well. They allow users to conduct tests of their phones actual network speed and signal strength.

How to check the signal strength on Android

As it’s shown above, users can use specialized apps to check the existing signal strength. Moreover, Android users can also use field test mode under the setting menu.

Android Field Test Mode

  1. Go to setting
  2. Tap About Phone
  3. Select Status or Network
  4. Tap SIM Status
  5. Your Signal Strength is read in dBm

How to check out a nearby cell tower location?


Upon installation to a signal booster, to ensure the cell phone signal is the greatest it can be, you need to find out a place at your building where has the strongest signal and mount the outdoor antenna. You may use the above methods to check, but it may take times. It’s best to point the outdoor antenna to the direction of the nearest cell tower on your carrier. Below are some resources recommended to locate a nearby cell tower.


Specialized APPS:

4 thoughts on “How to check out a nearby cell tower location?

  1. Robert Armstrong says:

    Thanks for the info on signal strength testing for android phone (I had just tested from info from a search result above yours). Result: -111 to 112 dbm (had 2 bars). Is there a way to LOCK THE SIGNAL BEFORE AND THEN DURING THE TEST,Then keep a data record? That would show if 5G, LTE, /!l (exclamation ❗ mark inside triangle) etc was on steadily or varying, as mine does, but you can’t notice it all the time. Thanks again.

    • Fay says:

      Appreciate for test method sharing, but actually no need real-time check RSSI value, all of signal amplification records could be checked in Signal Supervisor APP.

    • Fay says:

      Signal Booster is usually a kit for improving cellphone signals inside the vehicles, homes or buildings. It includes outside antenna, inside antenna, booster itself, cables, installation accessories.

      Signal amplifier is a power amplifier, device which amplifies weak signals and make them stronger.

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