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Why I'm Testing Another Mobile Network

My main fibre connection to the house recently went down for around 24 hours.

It got me thinking: if my fixed broadband connection disappeared again, could I use a mobile network as a useful backup — and which network would actually be fast enough to make that practical?

There's another reason for the experiment. My current mobile contract is coming up for renewal, so rather than simply renew with EE, I wanted to see what the alternatives were.

That led me to try a different approach: keep my existing EE SIM, add a Talkmobile eSIM using the Vodafone network, and actually test the two side by side.

Rather than relying on coverage maps or signal bars, I want to find out which network works best where I actually use my phone.

Finding a Suitable Mobile Mast

Before choosing the network, I did some research using CellMapper, a crowd-sourced mobile network mapping site.

It provides considerably more information than a normal coverage map, including individual cell sites, frequencies, cell information, signal measurements and the approximate direction of each sector.

The data isn't perfect, but it gave me a useful starting point. I could see a nearby Vodafone site with sectors pointing broadly towards my area, so Vodafone seemed worth testing.

CellMapper can also be used to investigate EE and other networks, which makes it useful for comparing the two rather than relying entirely on the networks' own coverage maps.

Why Use an eSIM?

My iPhone supports dual SIMs, so I could leave my normal EE SIM in the phone and add Talkmobile as an eSIM.

Talkmobile uses the Vodafone network, allowing me to switch mobile data between EE and Vodafone on the same phone and from the same location.

That makes for a much fairer comparison than using two different phones or physically swapping SIM cards.

The Talkmobile eSIM was ready about 30 minutes after ordering.

I chose a 30-day rolling plan so I could test it for a month without committing to a long contract. I also phoned Talkmobile rather than ordering entirely online and they added an extra 5GB of data for the same price as the advertised deal.

How Frequency Affects Mobile Coverage

Another thing that affects mobile coverage is the frequency being used. In general, lower frequencies travel further and penetrate buildings more easily, while higher frequencies can provide more capacity and speed but don't travel as far.

Technology Typical frequencies General behaviour
Analogue TV VHF / UHF High-power broadcasts covering large areas
Freeview UHF Digital TV using spectrum much more efficiently
2G / GSM 900 / 1800 MHz 900 MHz gives good range and building penetration
3G 900 / 2100 MHz Lower frequencies give better coverage; higher frequencies more capacity
4G 800 / 1800 / 2100 / 2600 MHz A mixture of coverage and capacity bands
5G 700 / 2100 / 3500 MHz+ Lower bands cover further; higher bands provide more capacity but shorter range

There's also an interesting link between old analogue television and modern mobile networks. When analogue TV was switched off, some of the spectrum it had occupied was freed up. The 800 MHz band was subsequently used for mobile services, including 4G, and the 700 MHz band was later cleared from Freeview and made available for mobile use.

That means my Vodafone connection on Band 20 at 800 MHz is using a frequency that was once part of the television spectrum.

It also helps explain why that connection can work well inside a house. 800 MHz is a relatively low mobile frequency, so it has useful range and building penetration compared with higher-frequency mobile bands.

Of course, frequency isn't everything. The amount of spectrum available, how busy the cell is, interference, the phone itself and the network configuration all affect the speed you actually get.

Understanding Mobile Signal Strength

Signal strength figures can look confusing because home Wi-Fi and mobile networks use different measurements. As a rough guide, these are the sorts of readings you might expect:

Signal Home Wi-Fi 4G / 5G
Excellent -30 to -50 dBm -40 to -80 dBm
Good -50 to -67 dBm -80 to -90 dBm
Usable -67 to -75 dBm -90 to -105 dBm
Weak -75 to -85 dBm -105 to -115 dBm
Very weak Below -85 dBm Below -115 dBm

These figures are only a rough comparison because Wi-Fi and mobile networks measure radio strength differently. But they give a useful idea of why a number such as -90 dBm isn't necessarily terrible on a mobile network.

In my test, EE measured -119 dBm, which is very weak for 4G, while Vodafone measured -89 dBm, giving me a considerably stronger mobile signal.

And as the results below show, a stronger signal doesn't necessarily mean a faster internet connection.

The First 4G Test

The first test produced an interesting result.

I used the iPhone's Field Test Mode to look beyond the normal signal bars and record some of the actual radio measurements. On the iPhone, you can access it by dialling *3001#12345#* in the Phone app.

This is how I get the results for the table below. Field Test Mode shows the technical signal information for the mobile connections on the phone, allowing me to compare the different SIM and eSIM providers side by side on the same phone screen.

My EE connection at home normally gives me around 35 Mbps download and 2 Mbps upload.

Measurement EE Vodafone
Connection 4G/LTE 4G/LTE
PCI 384 182
Band — 20
Bandwidth — 10 MHz
RSRP -119 dBm -89 dBm
RSRQ -14 dB -13 dB
SINR 0.8 / 0.2 dB 9.5 / 13.6 dB
Signal indication 2 bars Full bars
Download ~35 Mbps 24 Mbps
Upload ~2 Mbps 5 Mbps

More Testing Around the House

The first test was only the beginning.

I've tested different parts of the house and the results have varied considerably. Download speeds have ranged from around 10 Mbps to 25 Mbps, while upload has been much more consistent at around 5–6 Mbps.

At one point I was seeing only around 1 Mbps download, which makes capacity issues look increasingly likely.

I've now tested around the house, including the loft, and the Vodafone connection has generally looked very good from a radio-signal point of view.

Interestingly, YouTube streams perfectly well, even when the Speedtest result isn't particularly impressive.

That's another reason not to judge a mobile connection entirely by one Speedtest result.

I'll also repeat the tests at different times of day, particularly earlier in the morning when the cell may be quieter.

The Talkmobile Data Allowance

I did discover one slightly odd thing after activating the eSIM.

Although Talkmobile describes the plans as 30-day rolling, my first allowance period wasn't a fresh 30 days. I was given 20GB, but my account showed only 12 days remaining until the allowance renewed.

So the first allowance period can already be part-way through when you join.

Usage can be checked through the Talkmobile online account, where there's also an option to top up data if required.

What I'm Actually Trying to Find Out

There are really two parts to this experiment.

First, how well does Vodafone work at home compared with EE?

Second, how does it perform when I'm out and about?

A network might be mediocre at home but excellent a few miles away, or the other way around.

I'll therefore be looking at:

  • 4G coverage around the house
  • Download and upload speeds
  • Signal strength and quality
  • Performance at different times of day
  • Coverage around the local area
  • Streaming
  • Voice calls

I'm also interested in whether a good data connection translates into a good calling experience. I'm not going to assume that it does — I'll test calls separately.

Conclusion So Far

That's the whole point of the experiment: not which network looks best on a coverage map, but which one actually works best for me.

The next step is to test an O2-based 30-day rolling eSIM, followed by an EE-based 30-day plan. They don't necessarily need to be bought directly from O2 or EE — a provider using their network is fine, as long as I can properly test the network itself.

Once I've tested all three networks in the places and at the times that matter to me, I'll compare the results and look at the cost of the plans as well.

I'll update this article with the final results and my choice of network once the testing is complete.

Published By Tudor Gibson

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