London’s skyline is a thing of beauty – glass giants stretching into the clouds, offering million-pound views and housing some of the UK’s most prestigious companies.
But while these towering beauties might dazzle your eyes, your mobile signal is probably weeping in a corner. Why? Because height may impress clients, but it doesn’t guarantee you can make a call or load a document without Wi-Fi.
Let’s talk about the hidden problem in some of London’s most iconic office buildings: indoor mobile connectivity – or, more accurately, the lack of it.
Connectivity – Now a Dealbreaker for Office Tenants
Let’s stop pretending mobile coverage is a “nice-to-have.” According to the latest report from Boldyn Networks, it’s officially crossed over into dealbreaker territory:
💸 94% of tenants are willing to pay more in rent for better mobile connectivity.
📈 77% rank fast, reliable connectivity as a top priority when choosing office space.
📲 63% believe full mobile coverage should simply be a given — like heating, lights, or functioning elevators.
In other words: if your building has flaky coverage, tenants aren’t just mildly annoyed — they’re making different leasing decisions.
Mobile connectivity is now core real estate infrastructure. Just like power, plumbing… and, yes, maybe even decent coffee in the lobby. Without it, you’re not just missing bars on a phone — you’re missing revenue, renewals, and relevance in a hybrid, hyperconnected workplace.
Modern Work = Mobile-First
This isn’t about streaming TikToks in the break room. It’s about business:
- Employee efficiency: Dropping calls when you step into the elevator or garage is not ideal in 2025.
- Security: Many companies are blocking employees access to public/guest Wi-Fi due to security risks and recommend using mobile hotspots instead.
- The 5G workstyle: Businesses are equipping employees with 5G laptops and secure SIM-based access.
And if mobile-first is the new standard for work, shouldn’t your building be mobile-ready?
Radio Reality – Why It’s So Bad Up There
Indoor mobile coverage typically comes in two flavors:
Outdoor-to-indoor (macro coverage): This relies on the outdoor mobile network — antennas on nearby rooftops or towers — to reach inside the building.
Dedicated indoor systems (indoor DAS/small cell networks): These are purpose-built solutions installed inside the building to provide strong, consistent coverage throughout.
The challenge? Most commercial buildings, especially newer or refurbished ones, are built like bunkers (but prettier).
🏗️ Tall buildings = a lot of floors to reach.
🧱 Thick concrete walls = signals get absorbed before they even make it inside.
🪟 Energy-efficient glass (like Low-E) = blocks up to 99.9% of radio signals.
This means that macro networks struggle to penetrate, especially to the middle and upper floors. In many buildings above 10–15 stories, the mobile signal barely gets past the lobby — if that.
Without a dedicated indoor system, tenants and building systems are left relying on spotty, inconsistent, or even non-existent coverage. And in an era of hybrid work, connected devices, smart building systems, and high tenant expectations, that’s no longer acceptable.
Signal Strength 101: RSRP for the Win
Let’s break down the mobile signal basics with the help of our trusty friend: RSRP (Reference Signal Received Power). Think of RSRP like the volume of music coming from your neighbor’s apartment.
🎵 If it’s strong enough to clearly hear your favorite song—great! If it’s faint, crackly, and leaves you guessing the tune—not so great.
✅ Crystal clear | Signal strength: Better than -80 dBm RSRP What it means: Fast and stable connection. Calls are smooth, apps are snappy, and your playlist keeps the vibe alive. |
⚠️ Good enough | Signal strength: -80 to -100 dBm RSRP What it means: Usable for most things, but don’t expect perfection. A call might dip, a page might lag — it’s serviceable, not stellar. |
🚫 Struggling | Signal strength: Worse than -110 to -100 dBm RSRP What it means: Apps freeze, video buffers, calls drop. You’re in the frustrating zone where things sometimes work… and sometimes don’t. |
❌ Highly unreliable | Signal strength: Worse than -110 dBm RSRP What it means: Very weak and unpredictable. Maybe a message slips through now and then, but don’t count on it for anything important. |
The Study: London’s 12 Tallest Office Towers
To get a clear picture of mobile connectivity in some of the UK’s most high-profile buildings, we focused on a very specific sample: the 12 tallest office towers in London. These buildings aren’t just tall — they’re iconic. If you’ve ever looked at the London skyline, you’ve seen them:
The Shard. The Gherkin. 22 Bishopsgate. One Canada Square. The Cheesegrater. And the rest of the dozen that define modern London’s vertical business landscape.
Together, these 12 towers represent nearly 1 million square meters of office space — home to thousands of employees, businesses, visitors, and digital systems.
And if you were to stack them on top of each other (don’t try this at home), they’d reach nearly 3 kilometers into the sky. That’s higher than Mount Fuji, and well into “you’ll need a pressurized suit” territory.
We analyzed mobile coverage in these buildings using data from Ookla, the global leader in network performance measurement — the same folks behind Speedtest.net. Their platform collects billions of real-world signal samples from mobile phones around the world, giving us an unparalleled, data-driven view of how mobile networks actually perform inside these buildings.
Why these towers?
Because they’re tall, complex, and often equipped with the latest in energy-efficient materials — exactly the kind of environment where outdoor mobile signals struggle, and where strong indoor coverage matters most.
The goal: to understand the real-world performance of mobile connectivity in the UK’s flagship commercial buildings — and what the data tells us is… let’s just say, not entirely comforting.
What We Found (Spoiler: It’s Not Great)
Below you have a summary of how the buildings perform in way of giving its users indoor mobile connectivity. Roughly 39% of all this prime real estate—around 370,000 sqm—has poor or highly unreliable mobile coverage.
That’s nearly £370 million in annual rent at risk if we go by an average of £1,000/sqm/year.
✅ Crystal Clear – 17%
⚠️ Good Enough – 44%
🚫 Struggling – 21%
❌ Highly unreliable – 18%
Here you can see an example of how actually measured mobile connectivity can be visualised in a tall building.
Grey color reflects really poor connectivity and the it’s easy to see that the upper parts have a more difficult time securing good indoor mobile service.
Leaderboard of Shame & Fame
🥉The tenants and guests/shoppers in the worst performing building can expect to have a tough time using the mobile network 72% of the times
🥇The best performing building secure good enough or crystal clear service 93% of the time
😬 4 buildings disappoint their tenants and users more than 50% of the time
What This Means If You Own or Manage One of These Buildings
Let’s be blunt. If your building has poor or unusable indoor mobile coverage, you’re facing:
- Unhappy tenants – and they might leave or negotiate lower rents.
- Longer vacancy periods – tenants prioritise connectivity when choosing where to move.
- Lower building valuation – poor digital infrastructure can hit your bottom line just like bad ventilation or slow elevators.
💡 The good news? This is a solvable problem.
Installing indoor 4G/5G infrastructure transforms your building from a digital dead zone into a productivity powerhouse.
📍 Curious how your building scores?
We can analyse mobile coverage in your property — remotely using big data, or through an in-building walk test.
✅ Data-backed.
✅ No hassle.
✅ Results you can act on.
Final Thought
Beautiful buildings deserve beautiful signal. If you’re paying a premium for a top-floor view, you shouldn’t have to run down three flights of stairs just to send a text.
If you want to know what the mobile experience is like in your building—or if you’re ready to do something about it—give us a shout.
References
Big Data supplier: https://www.ookla.com/cell-analytics
Boldyn Report: https://resources.boldyn.com/cre-report-uk/
