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  • How does Cel-Fi Work?

    Cel-Fi consists of two units: the Window Unit (WU), and the Coverage Unit (CU). Users place the WU in an area with the strongest signal from the mobile network. The CU is then either placed in the centre of the home or office, or in the area where the best signal quality is most needed. The two units communicate wirelessly with one another enabling the CU to effectively produce a 'bubble of quality signal' throughout the home or office, resulting in significantly better voice quality and greater data throughput. The WU and the CU are placed at varying distances apart, but in general an indoor distance of up to 20 meters, or 66 feet, is common.

  • Is the Cel Fi RS2 legal?

    Yes the Cel Fi RS2 is legal. It is allowed by Ofcom (see http://licensing.ofcom.org.uk/radiocommunication-licences/mobile-wireless-broadband/cellular-wireless-broadband/policy-and-background/femtocells-smart-repeaters/) and it has also been approved by the individual networks. In the UK (and several other countries) Cel-Fi devices are ultimately under the control of the mobile networks, i.e. the network has the ability to disable Cel-Fi devices in a particular area, without any user input.

    Mobile operators have historically adopted an extremely strict policy against the use of user-installed repeaters and boosters on their networks as they caused interference and damage to the performance of the networks. Because of its unique intelligent features, Cel-Fi is the only user-installable booster permitted in the UK and most other countries.

  • What is the difference between RS1 and RS2?

    The RS1 has lower capacity than the RS2, in terms of the number of radio channels it supports. The RS1 was deployed to a limited extent by T-Mobile UK and in tiny amounts by O2 UK. It is no longer being supplied in the UK.

    The RS2 has 3x the radio capacity of the RS1 and is deployed in the UK with a configuration that allows the mobile operator whose network it is configured for to turn it off by setting particular parameters in the network.

    In all other respects the RS1 and RS2 are the same, they are locked to a particular network, only boost that network's radio frequencies and implement hardware and software algorithms that completely protect the network from the harmful effects usually associated with repeater products.

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

    Cel-Fi relies on intelligent, self-organizing algorithms to maximize 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 booster authorized and approved by the communications commissions in Australia and the United Kingdom, and the first consumer 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.

  • How does Cel-Fi differ from a broadband repeater?

    Cel-Fi does several things:
    1. A Cel-Fi device only boosts specific UMTS carrier frequencies (5MHz channels, up to 3) and not the whole band.
    2. Cel-Fi will only boost the pre-configured UMTS carrier frequencies if they actually contain a valid UMTS signal and are for the correct network (i.e. the Cel-Fi device can lock onto the UMTS pilot channel, like a phone, and read broadcast information, such as the network identity or 'PLMN-ID' then determine what to boost)
    3. Cel-Fi automatically limits its boost when close to the base station (based on a calculation of the actual RF path-loss) and so will never boost thermal noise to a level where the base station's uplink performance will be damaged
    4. Cel-Fi is unconditionally stable and will never oscillate - oscillation is usually a common and serious problem with traditional repeaters which causes power spikes that degrade the base station's uplink performance.

  • What technologies does Cel-Fi support?

    The current version of Cel-Fi supports 3G WCDMA/HSPA+ technology commonly referred to as 3G, 3G+, it does not support 4G LTE.

  • What is IntelliBoost?

    The Cel-Fi's IntelliBoost Baseband Processor is the first core processor designed specifically to optimise the indoor transmission and reception of 3G wireless signals. With advanced filtering, equalization and echo cancellation techniques, Nextivity has developed an embedded architecture which delivers unprecedented in-building data rates and pervasive 3G connectivity. The IntelliBoost processor ensures that Cel-Fi products never negatively impact the macro network while providing maximum coverage. By continuously monitoring the gain and making real-time adjustments, the system will never overdrive the base station or raise the noise floor.

  • What frequency is used to communicate between the two units (the Window Unit and the Coverage Unit)?

    Cel-Fi uses channels from both the U-NII-1 (either 5.15-5.25 GHz OR 5.25-5.35GHz) and the U-NII-2 block (5.47-5.725 GHz) to communicate between the Window Unit and the Coverage Unit.

  • What's the radiation level of Cel-Fi RS2?

    So is the Cel-FI RS2 Signal booster 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 a SAR rating. In any case the power we emit is no greater in general than other consumer wireless networking devices and smart phones.


  • What networks are compatible with the RS2?

    We have four RS2 units available for Three, EE, Vodafone or O2. However, within these networks there are also Mobile Virtual Network Operators. Please see the additional networks these units can support below:

    EE O2 Three Vodafone
    Mobile Virtual Network Operators
    • Virgin Mobile
    • BT
    • LIFE Mobile
    • Blyk
    • Vectone Mobile
    • Lyca Mobile
    • Family Mobile
    • Utility Warehouse
    • Tesco
    • Lyca Mobile
    • Giff Gaff
    • BT Mobile
    • Lebara Mobile
    • Mobile by Sainsbury's
    • Talkmobile
    • TalkTalk Mobile
    • Truphone

    Please note that MVNOs may occasionally change their host network. If this happens, please contact us about reconfiguring your Cel-Fi unit.

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

    No, Cel-Fi products do not require network activation or provisioning.

  • Does the RS2 unit I purchased for Orange or T mobile with the SD card work with EE?

    Yes it does, when you received these RS2 units with the SD card you would have got one SD card for Orange and one for T mobile. If you insert the T mobile SD card this will configure your RS2 to be compatible with EE.

    Alternatively, remove and discard the SD cards, then update the Cel-Fi device to the latest operating software and configuration for EE: go to http://cel-fi.com/ee-upgrade and follow the instructions.

  • Is Cel-Fi operator or service provider specific?

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

  • Does the Cel-Fi RS2 work with 4G?

    Cel-Fi RS2 will only improve the 3G signal and it's not 4G LTE compatible. It's worth mentioning that 4G is a 'data only' service, i.e. for Internet, downloads, video streaming etc. - the moment you make a phone call, your phone will revert to 3G (or even 2G) to make the call.

  • Does the Cel-Fi RS2 work for multiple networks?

    One Cel-Fi RS2 unit can be used for one network only. Therefore if you need to support two different networks you need two units.

  • Will Cel-Fi work with my iPhone?

    Yes! All versions of the iPhone (including 5S and 5C) are supported on new RS2 Cel-Fi systems sold on this web site.

  • What is the range and how many devices can the RS2 boost?

    The range of the Cel-Fi RS2 depends on building construction; we quote 20-metre radius as typical, but it can be smaller or bigger depending on:

    • the building construction
    • strength of the signal at the Window Unit and
    • physical separation of the Window Unit and Coverage unit (more separation = more boost).

    There is no limit to the number of devices that can be attached to the network via Cel-Fi. The number of calls the unit can support depends on how far away it is from the serving base station (shown by the number of coverage bars on the display of the Cel-Fi Window Unit). Where the coverage is weak (1 or 2 bars on the Cel-Fi Window Unit) the unit may support as little as 3-6 calls. Where the coverage is good (4 or 5 bars on the Cel-Fi Window Unit) the unit can support 20 calls or more.

  • Does the Cel Fi RS2 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.

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

    Cel-Fi utilizes 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.


  • I have followed the set up instructions but I am getting an error message...

    Error code Meaning Resolution
    Coverage Unit Shows Value of '0' The coverage unit is too close to the window unit Move the coverage unit further away from the window unit
    E4 Window unit is overheating Make sure the vents on the unit are not blocked. Move the unit to a cooler area. The system will start working normally when it cools down
    E3 Coverage Unit is overheating Make sure that the vents on the unit are not blocked. Move the unit to a cooler area. The system will start working normally when it cools down.
    E1 No signal on the Window Unit Try moving the window unit to another room or area where you have coverage. (use your mobile phone to find the best 3G coverage)
    Red Status on Coverage Unit There is a hardware error Try resetting the coverage unit by unplugging it and then plugging it back in. If problem persists return system for a service
    7 segment display on the CU is cycling for more than a minute The unit is taking longer than normal to make a link Wait for the display to stop cycling, this could take several minutes. Move away from WiFi devices
    No lights on Coverage Unit display There is no power Is it plugged in? Is there power at the outlet? Try exchanging the power supplies with the window unit to see if the power supply is defective.
    Centre three bars on signal display of Window Unit are flashing It means network operator data is missing. Contact Cel Fi customer services
    No segment lit on signal display of the Window Unit and status indicator on solid green Cel FI is not receiving any 3G signal Move the window unit to another room or area where you have more coverage. (use your mobile phone to find the best 3G coverage)
    Status indicator on the Window Unit is on solid red There is a hardware error Reset the window unit by unplugging it and then plugging it back in again. If problem persists contact Cel-FI customer services.
    Status indicator on Window Unit is flashing green for more than a minute The window unit is attempting to complete regulatory compliance Wait for the status indicator to stop flashing, this could take several minutes
    No lights on Window Unit There is no power Is it plugged in? Is there power at the outlet? Try exchanging the power supplies with the coverage unit to see if the power supply is defective.
  • I've installed Cel-Fi, but my mobile phone's signal strength is the same.

    It is very likely that you are using an iPhone, which measures your signal differently than other devices. Even if your Cel-Fi booster is installed correctly and the service you experience is substantially improved, your iPhone may not show you these improvements in relation to the number of signal strength bars on the phone. To learn more about how iPhones display signal strength, click here.

  • Contact Us

    • Cel-Fi.co.uk
    • Frequency Telecom Ltd
    • 44 Barwell Business Park
    • Leatherhead Road
    • Chessington
    • Surrey
    • United Kingdom
    • KT9 2NY
    • Tel: +44 (0)20 8397 2222
    • Fax: +44 (0)20 8397 9999

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