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How to Test Mobile Signal Strength in the Building and Prevent Communication Problems

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Most commercial buildings were constructed many years ago when mobile devices and internet connectivity didn’t exist or were in their early stages. As such, weak or poor mobile signal is by far the most common complaint of tenants and businesses occupying such spaces. But, before you’re ready to fix your building’s bad network once and for all, you should know what makes a good mobile signal strength and how to measure it.

Despite popular opinion, checking the bars on a phone is not a good test of mobile signal strength. It is because there’s no law tying signal strength to the number of bars on the phone. It’s up to the phone manufacturer and carrier to determine the strength of 1, 2, 3, or full bars on their network. 

In this article, we’ll break down how to check mobile signal strength for a building and review phone signal quality for all available networks. We’ll also share tips and tricks for accurately gauging signal strength in specific areas in your building. Let’s hit the ground running!

What Makes a Good Mobile Signal Strength?

One professional, best-in-class way to test mobile signal strength inside the building is to determine its decibel-milliwatts, or dBm for short. Mobile signals are basically radio waves operating within specific frequencies. Signal strength can range from -30 dBm (the best possible signal) to -120 dBm (almost no signal/dead zones).

Any signal stronger than -107 dBm is considered usable, and it’s rare to find it more potent than -50 dBm in the telco market. Typically, from -115 dBm downwards is useless, as calls would drop, data speed would be painfully slow, texts would take a long time to send, and videos buffer. Around -120 dBm, it is pretty much dead. 

Here are signal ranges and what to expect from each:

Signal Strength (dBm)Expected Result
-50 to -79Excellent signal strength
-80 to -89Good signal strength
-90 to -107 Average signal strength
-108 to -114Poor signal strength
< -120Dead

Important: This chart is a benchmark. Every carrier has its own dBm to bars conversion standards. 

Factors Influencing Signal Strength

Certain factors can influence the strength of a signal inside a building, which usually include:

  • Weather conditions like storms, rain, and fog distort mobile signals. 
  • Radio frequency interference from wireless technologies such as microwaves, cordless phones, and other appliances reduces signal strength. 
  • The height of a building, its layout, and building materials like concrete and steel can obstruct signals from reaching devices. 
  • Being too far from the nearest cell tower will result in a far-from-optimal signal strength.
  • Increased user volume in office buildings and densely populated areas causes network congestion.
  • Physical obstructions and other potential interference sources like trees, other buildings, mountains, etc., block mobile signals.

If you measure the mobile signal strength of a building, and it doesn’t hit the benchmark because of one of the above reasons, you absolutely need a mobile phone signal booster or its alternatives. Signal boosters eliminate signal dead zones and improve signal strength to a level of -100 dBm or higher. 

How to Measure Mobile Signal Strength 

Simply access your mobile device’s “field test mode” to measure mobile signal strength in decibel-milliwatts. This can be found in the “About phone” or “Network” settings for Android or by typing in a *#*#4636#*#* code for iPhone. DBms will be represented as RSRP signal strength. But of course, it's more of a DIY method, and you will require professional signal testers for more precise measurements.

But, whatever you choose for a professional test of mobile signal strength, it’s crucial to know how to accurately take measurements to reflect the true state of a mobile signal in your building. So, here are our best practices for how to measure mobile signal strength and provide proper in-building mobile signals in new and old commercial properties: 

1. Test signal strength at different points in the building

Testing signal strength at different pivotal points in a building is also known as grid testing. Test mobile signal strength for the building, highlighting spots where calls frequently drop and areas where people go to make uninterrupted calls. We recommend walking around the property to note areas where you tend to lose network coverage and map them out. 

Take several dBm readings, then compare them. Consider getting an expert onboard to properly access your building’s coverage loopholes, simulate emergencies, identify the specific culprits causing poor signal inside the building, and determine how to fix the problem. 

Grid testing is vital for robust mobile coverage in building areas with signal-related issues and interference.  

2. Test one network at a time

Wondering why your 4G is so slow while 5G works perfectly? Some networks provide better 4G or 5G coverage in some areas. Therefore, it’s essential to test mobile signal strength across all carriers. Identifying gaps in their coverage is critical, especially in commercial buildings, where there may be more areas with weak signals than strong ones.

3. Forget the bars

The mobile signal bars in the upper right corner of your mobile device is mostly there as a visual representation of cellular signal. It’s basically the Joe Bloggs of signal strength testing and doesn’t paint the full picture. While bars are an easy point of reference for laymen, they can vary greatly and often depend on the phone manufacturer and carrier network. Generally, a full bar doesn’t equate to great coverage, and it’s recommended to ignore the bars when testing mobile signal strength in office buildings or for your commercial property. 

4. Face important key performance metrics

One important KPI to monitor when accessing a building’s signal strength is the radio frequency quality. Many factors like weather, network congestion, and more will affect signal quality. Go to areas where calls drop and data connection is interrupted and look out for the RF interference culprit in question. From our experience, one of the most common determinants of signal strength is RF interference. Therefore, learning how to test mobile signal strength in a building without spectrum analysis is a waste of time. It involves identifying these RF factors such as trees, building materials, and other signal degradation sources.

5. Invest in the best signal strength boosters

Plenty of factors have a role to play in determining the best signal strength booster for your building. It’s not enough to choose a booster type because it worked for some other venue. Before we delve into these signal strength boosters in details, know this: it’s best to involve a signal test consultant well versed in signal strength and its influencing factors. An expert is in the best position to professionally test your building’s mobile coverage and decide whether it's reasonable to deploy a signal booster. 

How to Provide Robust Mobile Signal Strength for Office Buildings 

Once you’ve tracked down your building’s signal strength, it’s time to start exploring solutions for providing robust mobile signal strength in office buildings and commercial properties. We'll say this once: all the signal-improving apps, homemade antennas, and other DIY devices are useless when it comes to enhancing your mobile connection. In fact, they can even make it much worse. So, here are your real working options for how to boost a phone signal

1. Mobile Signal Boosters

If you want robust solutions, it’s recommended that you seek help from qualified signal-boosting experts like UCtel. We’ll inspect your property and develop a strategic layout for your signal-boosting solution. It's even possible to improve the signal of specific carriers or network types (3G, 4G, and 5G). You can expect for the connection to be as good as outside, meaning they’re a good fit for buildings with weak signals but good outside coverage.

2. Private 5G Network

5G is the future of wireless connectivity, but it’s slowly being rolled out in every part of the world. However, you can take matters into your own hands by adopting a private 5G network, which is similar to the public 5G network but allows owners more control over it. This next-gen dedicated private network has wide and deep coverage, low latency, strong security, and is easy to deploy. This is a robust solution for every commercial building, such as hospitals and factories, that rely on fast and reliable networks for smooth operation. 

Consider UCtel as Your Trusted Partner 

Need help with how to check mobile signal strength for a building? Our friendly signal experts are at your beck and call. UCtel is a leading provider of mobile boosters and alternative solutions for commercial buildings and large venues. We specialise in user-friendly signal equipment, as well as unique RF systems for mobile, DAS, and private 5G networks. 

Signal strength is life! Come to us with your tales of poor signals, and we’ll make it right. Say hello or contact us via 0333 344 4417 for a free consultation.


Bars are pretty much meaningless, as they don’t really reflect signal strength. Instead, you should focus on professionally testing your building’s signal strength, which is essential for ensuring robust coverage. If you’d like to know more about measuring mobile signal strength in the building, simply get in touch, and we'll schedule a signal test in your building. See for yourself how good signal boosters and other signal-strength amplifiers can get. 


Find answer below or contact us to ask more about UCtel

What are the options for testing mobile signal strength inside the building?

You can test your building’s signal strength using your phone’s "field test" mode, buying professional signal testers, or contacting a mobile signal expert to do it for you.

Why is it important to measure mobile signal strength for commercial spaces?

To adopt suitable solutions and place them strategically around the building, you should determine your signal strength and where the dead zones are.

What is the best way to check mobile signal strength properly?

You should forget about the bars on your phone and focus on decibel-milliwatts readings. The best way to do this is to contact a team of professionals like UCtel.

Contact the team to discover how UCtel can improve your digital connectivity and communications.

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