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Cell phones have become essential tools for individuals and businesses, so it’s more important than ever to have good signal strength in your commercial building. A strong cellular signal ensures seamless conversations with fewer dropped calls and faster, more reliable transmissions when sending or receiving data. With a strong cell phone signal, mobile device users can conduct personal and company business over the phone without worrying about call quality or stability.

If you want to ensure that employees, customers and visitors can all use their mobile phones in your building, it’s helpful to know what constitutes good signal strength and how to determine whether you have it.

What Is Good Cell Phone Signal Strength?

The strength of a cellular signal can be accurately measured using decibel milliwatts, or dBms. Signal strength in dBms is expressed as a negative number and typically falls into a range that spans from -30 dBm to -110 dBm, with numbers closer to zero expressing stronger cellular signals. Essentially, this means that -77 dBm is a stronger signal than -86 dBm.

Signals better than -85 decibels are considered usable and strong, and you’ll rarely see a signal stronger than -50 dBm. At the other end of the spectrum, a signal that’s weaker than -100 dBm is likely too problematic to be useful — resulting in dropped calls and incomplete data transmissions.

Practically speaking, evidence of good cell phone signal strength in a residential or commercial building includes the following:

  • Call clarity
  • Few or no dropped calls
  • Minimal buffering
  • Rapid download and upload speeds

What Do Those Signal Bars on Your Phone Really Mean?

If you’ve unsuccessfully attempted to make a cell phone call in an unfamiliar location, then you’ve probably looked to see how many bars are displayed on your phone. You may even see bars displayed and still be unable to make calls. Unfortunately, this happens because these signal bars are not actually an accurate assessment of signal strength.

The trouble with your phone’s signal strength bars is that there’s no industry standard governing them, so they provide an indication of the relative strength of the cellular signal rather than an absolute value. In addition, because each phone manufacturer uses its own algorithm to determine signal strength, bars can vary significantly between devices from different brands. In other words, one phone may display only two bars despite receiving a stronger signal than a phone displaying three bars. It’s even possible for your phone to display four bars when you aren’t receiving a signal at all.

How Can You Determine the Cellular Signal Strength in Your Building?

If you have an active connection, both Apple iOS and Android devices have hidden field test modes that can accurately pinpoint cellular signal strength. Conducting a thorough site survey, which involves recording signal strength readings in and around your building and property, can be useful when determining whether your company would benefit from a signal booster.

Field test mode is typically easy to turn on, although instructions vary depending on the make and model of the device.

Android Phones

To initiate field test mode on your Android phone, open up your phone’s settings and select About Phone. Depending on your model, the signal strength can be found under Network or Status. You should also be able to find the network generation (5G, LTE, etc.) under Network Type.


Before accessing the field test mode on your iPhone, Wi-Fi should be turned off. This lets you see what network you’re connected to (5G, LTE, etc.). To turn off Wi-Fi, open Settings > Wi-Fi and switch it to Wi-Fi off.

LTE should also be switched off, since LTE signals may be measured differently than those of earlier generations. If your phone runs on iOS 9.3 or above, open your phone’s settings, select Cellular > Cellular Data Options > Enable LTE. Switch LTE to Off. If you’re running iOS 9.2 or below, open your phone’s settings, select Cellular and then Enable LTE. Turn LTE to Off.Poor reception may result from a number of conditions: distance, physical obstructions, weather, and high network traffic.

Once you’ve done this, open your phone dialer and pull up the keypad. Dial *3001#12345#* and press Call to launch field test mode. Instead of the traditional signal bars, you should now see a negative number. This is the signal strength reading in decibels. You should also see your carrier’s name and the network type.

In some newer iOS versions, you may see the words Back to Phone instead. If this occurs, hold down the power button. When you see Slide to Power Off, release the button. Then, press and hold the Home button until you return to your main screen. You should now see the signal strength in decibels. You can exit this permanent field-test mode by rebooting your device.

Other Types of Phones

Many other devices offer field test modes. Consult the manufacturer’s website or instruction manual for additional information.

Whether you use an Apple device, an Android or another brand of phone entirely, your app store likely offers options for assessing signal strength in decibels. Simply search for “cell signal” to see what apps may be available.

Taking Signal Readings

After you move to the location where you plan on taking the signal reading, wait 30 to 60 seconds for your phone to attain a signal. You can then find the signal strength as well as the carrier and network type (5G, LTE, etc.). For a professional to accurately assess the results of your survey, it’s important to take note of the network type in addition to the signal strength.

To conduct a survey of your property, repeat this process in different areas of your building and grounds. It’s also important to remember that the signal readings you take on your phone only apply to your individual carrier.

You may prefer to consult a professional, who can perform a comprehensive site survey using a professional-grade signal meter. This device can accurately detect and display signal frequency, strength and bandwidth.

What Causes Poor Signal Strength?

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Poor reception may result from a number of conditions: distance, physical obstructions, weather, and high network traffic.


If reception is poor, the phone may simply be too far away from the nearest tower. As a result, the signal may be weak or undetectable.

Physical Obstructions

A strong cell phone signal requires line of sight, so just about any object can block a cellular signal, decreasing reception. Objects that may block cellular signals include both man-made and natural items, such as:

  • Building materials: Steel, brick, concrete, wood, fiberglass insulation and even glass can diminish a cell phone signal.
  • Terrain: Hills, bluffs, mountains and ridges may all contribute to poor cellular signals.
  • Vegetation: Heavily forested areas may hinder cell phone reception. Shrubbery and other dense foliage can also block the required RF signals.
  • Dust: Dust particles in the air may also reduce the transmission of cellular signals.
  • Vehicles: Cars, buses and other means of transportation can block cellular signals, making it difficult to call while on the go.


Conditions such as electrical storms, high humidity, heavy cloud cover, wind and snow can reduce cellular signal transmission.

High Network Traffic

In densely populated urban areas, poor signal strength may be caused by the extreme amount of cell phone usage, particularly during peak times. This can result in sluggish data transfer.

Can Cellular Signals Be Boosted?

Yes. Buildings with a signal strength weaker than -85 dBms can benefit from a distributed antenna system (DAS), which captures and amplifies existing cellular signals. DAS systems can improve signal strength to -70 dBm or better and provide a cost-effective solution for ensuring better connectivity inside large buildings, including commercial spaces.

The Benefits of a Dual-Amplifier Passive DAS System

Although a DAS system may be an ideal choice for a business that’s looking for a cost-effective solution to poor cellular reception, there may be some signal loss due to the use of coaxial cables. A dual-amplifier configuration solves that problem. This design pairs a primary signal booster with a supplementary inline booster to compensate for signals lost over long lengths of cable. This pairing results in optimal signal boost for the building.

WilsonPro offers a wide selection of effective DAS cellular signal-boosting solutions to help you shore up connectivity at your place of business, no matter which carrier you use. WilsonPro’s systems serve the needs of commercial locations both small and large throughout North America.

To learn more about DAS solutions such as the Pro 1050 dual-amplifier system and the Pro 70 Plus line of cellular boosters, contact us today for a site survey or demo.

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