How to improve mobile signal with a booster

Last updated: 1 January 2022   By Dr Lucy Brown, Editor

Mobile phone users may need to improve their signal if they're struggling to make a call indoors.

Ofcom regulations on mobile indoor repeaters and in-vehicle repeaters mean that only a handful are available for customers to choose from.

With restrictions set to be overhauled in 2022, customers will likely get more choice, but the costs of mobile signal boosters could still be very high.

An alternative to a mobile signal boosting device is Wi-Fi Calling where customers use a fixed line broadband network to make a call or send a text instead.

mobile phone couple confusion

At a glance

Type What it does
Static indoor repeater Boosts signal for a property through an external antenna and an internal booster
Low-gain mobile repeater Boosts signal for a moving vehicle
Wi-Fi Calling Allows customers to make calls over a wi-fi network when the signal is poor

What types of mobile signal boosters are available?

Mobile signal boosters enable customers to improve their mobile signal indoors.

They are particularly useful for customers in rural areas who might be able to get a signal outside their property but can't get one inside. There are also mobile signal boosting options for customers in cars and other vehicles.

Below, we cover the different types of mobile signal boosters on the market and discuss the benefits and limitations of them.

Static indoor repeaters

If we think of a signal booster, one of the first that usually comes to mind is something that sits on the outside of a property and enhances the mobile signal in that way.

Often, a piece of equipment is installed on the outside of a property and it links with an internal piece of kit that helps boost the mobile signal inside the property.

These are known as static indoor repeaters but many of those on the market are illegal and not approved by regulator Ofcom because they interfere with other network equipment.

Right now, the only licenced models on the market come from Cel-Fi by Nextivity.

These repeaters work with all UK mobile networks (EE, O2, Three and Vodafone) and they have a 5-stage set-up process:

  1. Users should identify where the coverage problem is in the property and place the 'server' antenna there.
  2. The main unit should be placed in an area where there is coverage and it should be close to a window and as far away from the 'server' antenna as possible to avoid interference.
  3. Attach the antennae while keeping them as isolated as possible.
  4. Plug in the Cel-Fi power adaptor.
  5. Set up and optimise the boosting system using the Cel-Fi WAVE app to help determine how antennae placement could be improved.

As we mentioned, these are the only legal signal boosters on the market right now and they can be quite pricey.

The Cel-Fi SOLO Bundle with self-installation retails at over £1,000, meaning many customers will find them unaffordable,

That's partly why an unlicenced industry has sprouted up, yet with penalties of up to £5,000 and up to a year in prison, it's not worth the risk buying something that's currently unlicenced.

Ofcom take a dim view of illegal signal boosters mainly because they have the potential to disrupt other networks and cause interference.

However, they announced in November 2021 that they are changing the technical requirements for boosters during 2022.

We've got more information on this below, but it essentially means customers will have more options later this year and it should bring more competition into the market.

Even with this competition, though, it's really important that users double-check whether the repeater they're looking at is legal or not. A hefty fine on top of an expensive piece of equipment would be a costly way of trying to boost a mobile signal.

Low-gain mobile repeaters

Customers looking to boost mobile signals in vehicles or on boats can purchase a low-gain mobile repeater.

Again, the only legal options right now come from Cel-Fi and they have several options in their Cel-Fi GO range:

  • Vehicle bundle for cars, vans, caravans and motorhomes
  • Truck bundle for trucks
  • Marine bundle for marine vessels

There's a little confusion on Ofcom's website with old guidance suggesting low gain in-vehicle repeaters cannot be used in boats (possibly due to the 'in-vehicle' labelling) but Cel-Fi market their marine bundle as licence-exempt and, given their compliance with their other boosters, the confusion is more likely thanks to the wording on Ofcom's website.

These low-gain units consist of an external antenna and an internal booster that improves the signal strength inside the vehicle or boat to match what would be received outside.

Although these mobile signal boosters are designed for use in moving vehicles, it's worth pointing out they can't boost signal where there isn't one or where coverage is patchy.

According to the latest mobile coverage figures from Ofcom, 8% of the UK's landmass cannot receive a 4G mobile signal from any of the four mobile networks.

This overall figure down from 11% in 2018 but progress to tackle those not-spots is notoriously difficult, especially in Scotland where 18% of landmass isn't covered by a network.

Thanks to the Shared Rural Network (SRN) agreement between mobile networks and the Government, overall coverage is set to improve over the next couple of years.

Nation-specific targets mean that coverage in Scotland from at least one operator will rise to at least 91% yet that still leaves up to 9% of the country struggling to get a signal.

So, it's important to understand the limitations of a low-gain mobile repeater and understand that, while they may be useful for people in caravans and boats in semi-rural areas, even the best signal booster in the world would be unable to get a signal in some of the remote areas of the UK.

The pricing for Cel-Fi GO bundles ranges from £700 to £800 depending on which version we're looking at. Again, this is a serious investment and it won't be suitable for all.

One final point: these units are designed for use in moving vehicles rather than static caravans or anything like that. This also means that customers must adhere to the rules of the road and not use their mobile phone or other devices while driving.

Older boosters

Mobile customers may remember the days when mobile networks would supply their customers with a signal booster to improve the signal strength inside the home.

These fell into two categories: femtocell boosters that connected to a fixed broadband line to create a 3G mobile signal or standalone indoor repeaters that boosted an existing mobile signal.

Mobile networks could supply customers with femtocell boosters and indoor repeaters and, although there are still some on the wider market, they are illegal to use for the same reasons we've discussed above in relation to static indoor repeaters.

Unfortunately, technology has outpaced what these boosters offered to customers and all but one mobile network has completely abolished their femtocell booster service:

  • EE are phasing out their Signal Box support and no new units are available on their website. Signal Box will close completely at the end of June 2022.
  • O2 still allow business customers to purchase their BoostBox but consumers cannot.
  • Three stopped selling their Home Signal boxes in 2020.
  • Vodafone stopped selling their Sure Signal boxes in 2020 and the service will be completely withdrawn by September 2021.

Mobile networks haven't completely abandoned customers struggling to get a signal - they're advising they use WiFi Calling as we explore below.

It's also true that most of these signal boosters used 3G and that's unsustainable when networks like EE are looking to turn off 3G to free up space for 4G and 5G services.

Even so, the removal of network-provided femtocell boosters reduced the options for customers struggling to get a mobile signal indoors.

Wi-Fi Calling

The main reason mobile networks believe femtocell boosters are no longer required is thanks to the growth of Wi-Fi Calling.

Wi-Fi Calling allows a customer to use their home broadband network to make calls on their mobile and send text messages. It's the option that all mobile networks direct customers to use if their mobile signal is poor indoors.

However, there are a couple of drawbacks to Wi-Fi Calling that haven't been properly addressed yet:

  • It only works for smartphone customers (meaning those with basic older phones will be unable to use it)
  • Congested home broadband networks can lead to poor quality calls
  • Signal has been known to drop in and out as a user moves around the home

These issues might only affect small numbers of customers but, frustratingly, they may affect the very customers who most need Wi-Fi Calling.

For example, Ofcom figures for 2021 show over 120,000 premises across the UK are still unable to receive broadband speeds of 10Mb because they're in a hard-to-reach location.

Given the mobile coverage issues we've discussed earlier, it's likely some of the same people who need to boost their indoor mobile signal are those who can't get a decent broadband connection either.

Future of mobile signal boosters

The restrictions on mobile signal boosters are designed to protect networks and to stop interference from one booster getting in the way of other signals.

That's obviously important, but Ofcom recently acknowledged that the technical requirements had hampered competition and were driving up costs for customers.

So, during 2022 they plan to update the technical requirements for mobile signal boosters to enable more companies to bring them on to the market.

This should hopefully bring down costs as well as offering more choice to customers who are effectively limited to Cel-Fi devices at the moment - and those are only distributed by a handful of UK suppliers anyway.

As well as altering the technical requirements to allow most boosters to qualify, Ofcom will also publish a list of devices that meet the requirements to give customers more clarity over which boosters are legal and which ones aren't.

They stress they won't make judgement calls about which ones are best but having a list in one place will allow customers to choose a device that meets the technical requirements and help to avoid the masses of false claims about some devices being legal when they do not meet Ofcom's standards.

Conclusion: Are mobile signal boosters worth it?

Mobile signal boosters can be a lifeline to mobile customers in certain situations.

For those with poor indoor mobile reception or those who spend time travelling in a caravan or truck, the use of a mobile signal booster can help keep them connected when traditional coverage methods have failed.

The major problem with mobile signal boosters is simply the price.

It's unlikely that people struggling with their mobile signal at home will be able to afford £1,000 on a boosting solution and the cheaper options for cars, trucks and boats still cost up to £800.

Ofcom's new technical requirements may take some of the sting out of this, but these pieces of equipment still need to be complex enough to do their job without interfering with other signals. It means that prices may well come down, but not as much as consumers might like.

Mobile networks are focused on Wi-Fi Calling as an alternative option to indoor mobile signal boosters, but there are definite issues with them that mean they won't be suitable for every scenario.

Finally, it's important to reiterate that mobile coverage is improving more every year and, thanks to the Shared Rural Network, this should increase more rapidly in the next couple of years. Improved coverage won't help everyone boost their mobile signal but it's a good step forward.

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