Support and FAQs

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What is Cel-Fi?

Cel-Fi is Nextivity’s brand of self-configuring, environmentally aware, indoor coverage solutions. Each Cel-Fi system consists of two units. The Network Unit is placed in the area where the strongest native signal can be received from the carrier network (signal levels as low as -120 dBm are acceptable). The Network Unit comprises a transmitter and receiver which communicates with the cell tower. The Coverage Unit is placed in the center of the home, communicates wirelessly with the Network Unit and “lights up” the interior of the house with significantly enhanced signal levels, thus enabling better quality calls and greater data throughput.

Does the Cel-Fi require an internet or GPS connection?

No. The Cel-Fi system only needs to have at least 1 bar of native cellular signal, in at least one spot of your home to be able to cover your whole home or office space.

Is Cel-Fi Legal?

Yes Cel-Fi is legal. Cel-fi products are licence-exempt and fully comply with Ofcom's UK Interface requirement 2101 (IR2102) (UK) and ComReg S.I.No.283 of 2018 (Ireland).

Mobile operators have historically adopted an extremely strict policy against the use of user-installed mobile phone signal repeaters and boosters on their networks as they caused interferen ce and damage to the performance of the networks. It is for this reason that Ofcom consider many mobile signal repeaters as illegal. Due to its unique intelligent features, Cel-Fi is the only user-installable legal mobile phone repeater permitted in the UK.

What is a mobile signal repeater and is it legal to use one?

A mobile signal repeater is a radio device that works to boost mobile network coverage for users. They amplify frequencies from mobile network providers via reception antennas. All radio devices must meet regulations set out by Ofcom. These mobile phone signal repeaters are commonly known for interfering with mobile providers and as a result, Ofcom does not licence any signal repeater in the UK, making them an illegal technology.

Cel-Fi’s technology is more advanced, allowing mobile network providers the ability to monitor and regulate the use of Cel-Fi units themselves. For this reason, they classify as a Smart repeater and are considered a legal mobile phone repeater in the UK.

What is the difference between a mobile signal repeater and a Wi-Fi signal repeater?

Wi-Fi signal repeaters (or boosters) are used to extend the coverage of your Wi-Fi signal in buildings that have weak Wi-Fi connection. Commonly, these are used for home users and can increase the coverage of Wi-Fi within a building to areas that are not necessarily covered by original wireless router. Wi-Fi repeaters work by using built-in wireless routers to boost the current router transmission and amplify it.

Mobile signal repeaters such as Cel-Fi, work specifically to boost 3G and 4G data and voice coverage indoors for specific mobile networks. They focus specifically on improving voice clarity and reduce dropped calls for mobiles in areas with poor network coverage, as well as increasing download speeds and improving streaming and internet browsing on mobile broadband enabled devices.

Cel-Fi has the ability to turn one bar of signal into up to 5 bars and can amplify 3G and 4G from areas in a building with stronger coverage, to other areas that have little or no coverage within a 13,000 square foot radius - ideal for businesses as well as home use. Unlike Wi-Fi boosters, Cel-Fi does not require a broadband connection.

What technologies does Cel-Fi support?

All signal boosters are carrier approved to support 3G and 4G voice and data.

What's the radiation level of Cel-Fi units?

So are the Cel-FI Signal boosters safe? We actually test the Cel-Fi units like a phone for a SAR rating. Anything with a SAR rating of less than 2.0 is defined as 'touch safe'. Both the Cel-fi window unit and coverage unit have a SAR rating below 2.0.

Technically measuring SAR is usually only done for hand-held or body worn devices so WiFi routers generally don't have SAR ratings. In any case the power we emit is no greater in general than other consumer wireless networking devices and smart phones.

How do I know if my Cel-Fi system is compatible with an external antenna?

For two unit systems, the model number will have an _EXA suffix on the label (e.g. D32-1/3_EXA). Another way to determine external antenna compatibility is by looking at the back of the Network (Window) Unit, if there is a gold threaded fitting on the back of the unit then an external antenna can be used.

What is the range/radius of the Cel-Fi PRIME, GO X and QUATRA?

The 3 Cel-Fi units offer various ranges depending on your requirements. The Prime offers a radius of 1,000 square feet which is the equivalent of 1-2 rooms. The GO X offers a radius of 15,000 square feet for larger homes or small-medium business premises. The QUATRA offers a radius of 50,000 square feet, scalable up to 200,000 square feet by combining multiple systems together, for large business premises.
Factors which can affect range include:

  • The building construction
  • Strength of the signal at the Window Unit
  • Physical separation of the Window Unit and Coverage Unit (more separation = more boost)
Will certain materials in my building affect the unit from working correctly?

Certain building materials can affect the coverage of the unit. Older buildings tend to use more materials and have thicker walls and therefore radius coverage can be reduced. Modern construction materials such as foil-backed insulation and thermally-reflective glass can have a similar effect. If you would like to discuss a particular material in further detail with one of our advisors, please call +44 (0)330 353 0197.

How do I stop an order I've made?

We process orders very quickly via an automated process, so please contact us as soon as possible! We will do our best to stop the order or make the needed changes but please be aware that any orders already processed cannot be stopped. In this case, you would be required to follow the returns policy.

My order shipped and I want to cancel.

In the event we are unable to stop the order, we can of course offer you a return service. To request this, please fill out a returns form and email it to our support team, who will issue a Return Merchandise Authorization number (RMA#). After receiving the RMA#, please add this to the returns form and send it back with the unwanted order. Please note: Signal Boosters will not cover return postage costs for unwanted products. For further information visit our Returns section.

I ordered by mistake.

In the case of an incorrect order, we will gladly help you place the correct order and provide you with all the details you need to return the item that was ordered incorrectly. Please contact our customer service team as soon as you are aware of the mistake to avoid unnecessary shipping costs.


What networks are compatible with Cel-Fi?

We have Cel-Fi units available for EE, O2, Three or Vodafone. However, within these networks there are also Mobile Virtual Network Operators. Please see the additional networks these units can support on the link:

Mobile Networks and hosted Operators (MVNO)

Please note that MVNOs may occasionally change their host network. If this happens, please contact us about reconfiguring your Cel-Fi unit. Please also note that network operators have the right to shut down your system at any time, without notice.

Does it work with other Networks that are not listed above?

Cel-Fi is authorised for use by >180 mobile operators around the world. Of the world’s top 20 mobile operators, 13 have either implemented or are testing Cel-Fi. Cel-Fi UK only sell signal boosters configured to UK based networks. Other worldwide networks are available for a range of other countries; however, if a mobile network is not offered by Cel-Fi, the network is not available for purchase.

Does a Cel-Fi system have to be activated or provisioned on in the mobile operator's network?

In the UK all cel-fi units must be registered using a mobile app available for Apple/iOS and Android mobile devices. Other networks may or may not require registration.

Does Cel-Fi require maintenance or adjustments if changes occur to the serving mobile network?

No, Cel-Fi does not require maintenance, and it will automatically adjust to changing cellular network situations.

Is Cel-Fi operator or service provider specific?

Yes. Each Cel-Fi system is customised to work on an individual operator network.

Can you reconfigure the unit’s network if you change mobile networks?

Cel-Fi units can be re-configured to other networks using the Wave mobile app, if they were supplied by Units sullied directly through the UK mobile networks cannot be reconfigured to other networks.

Does the Cel-Fi work for multiple networks?

No. Cel-Fi is configured to one network at one time. Whilst it is possible to reconfigure the network on your Cel-Fi system, you will only ever be able to boost one network at one time.

Will Cel-Fi work with my Apple Device?

Yes. All iPad and iPhone versions are supported by Cel-Fi systems sold on this web site.

Does Cel Fi work internationally?

Cel-Fi units are not only set to particular frequencies, but they are locked to the network identity (referred to as the 'PLMN-ID'). Therefore Cel-Fi devices typically only work for the particular country and network they are sold to. Only Nextivity can create the configuration for any given network.

I am living outside the UK and want to purchase from this site. Will the Cel-Fi unit work in a different country?

Cel-Fi offer various configurations for a range of EU networks. Please contact us to find out if we can support you.


How do I install my Cel-Fi PRIME?

Watch our simple installation video for everything you need to know to install your Cel-Fi PRIME.

How do I install a Cel-Fi GO X?

Watch our simple installation video for everything you need to know to install your Cel-Fi GO X.

How do I install a Cel-Fi QUATRA?

Cel-Fi QUATRA requires a site survey and installation, please contact us for more information.

Technical Information

What is IntelliBoost?

The Cel-Fi's IntelliBoost is the first processor designed specifically to optimise the indoor transmission and reception of 3G and 4G wireless signals in silicon. With advanced filtering, equalization and echo cancellation techniques, Nextivity has developed an embedded architecture which delivers unprecedented in-building data rates and pervasive 3G and 4G connectivity. The IntelliBoost processor ensures that Cel-Fi products never negatively impact the mobile network while providing maximum coverage.

Why is 100 dB of gain so important?

System gain is critical to a booster’s performance because it tells us how much a signal may be improved and how beneficial the boosted signal can be. Example: If you have a low level signal such as -90 dBm per carrier, adding 100 dB of System Gain gives +10 dBm per carrier which can cover a large area. In contrast adding only 70 dB of gain would only give -20 dBm of signal per carrier which would only cover a very small space. Therefore a booster with a gain of 70 dB would need a very strong donor signal to be of much use, regardless of the stated transmit power that likely is going unused. In other words, the higher the gain of the booster, the better it will work, even when far away from a base station.

Does Cel-Fi cause significant degradation to mobile network quality as traditional repeater products often do?

Cel-Fi utilises an intelligent processor to actively adjust to the network environment. It uses multiple techniques including automatic gain control, real-time path loss analysis, and uplink signal gating to ensure that it never degrades the quality of the macro network signal or artificially raises the noise floor of the node B.

Is Cel-Fi a mobile phone signal repeater?

Mobile phone signal repeaters are classified as radio devices. They work to boost mobile phone signal, however, they can interfere with mobile operator networks and therefore are considered illegal as laid out by Ofcom.

Cel-Fi is different in that it is considered a smart repeater under the criteria set by Ofcom. A Smart Repeater is a mobile phone signal booster that is connected to a particular operator network and allows the host mobile network to control the device. Unlike, mobile phone signal repeaters, smart repeaters do not interfere with the mobile network’s coverage and are therefore considered a legal mobile signal booster.

What makes Cel-Fi different from other smart signal boosters?

Cel-Fi relies on intelligent, self-organising algorithms to maximise the area of coverage for users while ensuring that it does not compromise or interfere with mobile operator networks or impede other subscribers' signals. Cel-Fi does not require any new equipment or changes to existing network infrastructure, or mobile devices. Recognised for its superior design and effectiveness, Cel-Fi is the only consumer mobile signal booster authorised by the communications commissions in Australia and the United Kingdom, and the first consumer mobile signal booster fully compliant with the new Report and Order for signal boosters as defined by the Federal Communications Commission (FCC) in the USA, effective from March 2014. (AKA ‘FCC Part 20’).


I need some technical help with an error I am getting on my Cel-Fi unit.

Try running the “Cel-Fi Wave” mobile app on your Apple or Android mobile device and connect to the Cel-Fi Coverage Unit using Bluetooth. The mobile app will prompt you, if required, to enter registration information and offer trouble-shooting tips.

If the issue is still not resolved after carrying out the instructions on the troubleshooting guide, please contact a member of our customer service team using our contact form or on +44 (0)330 353 0197.