Answer first: the CVCD is a dual-band FDD LTE vehicle repeater that tunes Band 20 (800 MHz) for O2, Vodafone, Three and their MVNOs, and Band 3 (1800 MHz) for EE, ASDA, BT, Orange, T-Mobile, The People's Operator and Virgin 4G plus circuit-switched 2G voice and SMS. Its >=45 dB uplink and >=50 dB downlink gain recover a weak roadside donor through the body shell, while the 10 dBm low-power output spreads the recovered field across the driver, co-driver and passenger seats for up to 15 sessions. It stays Ofcom licence-exempt and carries UKCA, CE and RoHS marks, but it does not repeat 3G Band 1 at 2100 MHz, does not carry any 5G band, and is rated for the cabin or small caravan interior rather than a building or open estate.

Band 20 (800 MHz): The Long-Range Layer for O2, Vodafone and Three

Band 20 occupies the 800 MHz spectrum that Ofcom reallocated to 4G LTE after the analogue TV switch-off. Its low wavelength travels farther from the macro mast, bends around terrain and penetrates brick and foliage more cheaply than higher bands, which is why O2, Vodafone and Three deployed Band 20 as the rural and deep-road 4G layer. On a moving rural lane, Band 20 is the band that keeps a session alive between masts where the higher-capacity band fades.

Uplink and downlink frequency pairs for Band 20

A vehicle repeater works on a paired FDD block: the phone transmits on one block and receives on another, and the amplifier must repeat both directions without mixing them. The CVCD repeats the 832 to 862 MHz uplink and the 791 to 821 MHz downlink together so a phone that sends a request to the Band 20 tower hears the reply amplified inside the cab.

Why 800 MHz reaches the far mast but carries less capacity

Lower frequency propagates farther and passes a hedgerow or a hillside with less loss, but each MHz block carries fewer simultaneous data sessions than the higher bands. Band 20 is therefore the coverage band on a rural route: it keeps a phone connected at the edge of the mast's range, while EE's Band 3 carries the capacity where devices gather in a town or campsite. A Three user commuting through rural Wales, a Vodafone campervan, or an O2 Tesco or Giffgaff SIM relies on Band 20 being repeated indoors; the CVCD does that on the donor side before the >=50 dB gain and 10 dBm output spread it into the cab.

Band 3 (1800 MHz): The EE Capacity Layer and 2G Voice Path

Band 3 sits at 1800 MHz, the original GSM cellular band that EE and its family use for both 4G LTE capacity and legacy circuit-switched 2G voice and SMS. Its shorter wavelength carries more data capacity per block but attenuates faster through tinted glass, steel door skins and a caravan insulated wall, which is why it reads weaker inside a vehicle even beside a healthy town signal.

Uplink and downlink frequency pairs for Band 3

The CVCD repeats the 1710 to 1785 MHz uplink and the 1805 to 1880 MHz downlink so EE-family phones get both LTE data and the 2G GSM voice and SMS path on the same layer. An older feature phone, a passenger's handset, or a phone in an area where VoLTE has not yet been enabled still completes a normal call over the repeated 1800 MHz GSM layer rather than dropping to no service inside the vehicle.

Why EE customers need this band rather than Band 20

EE does not rely on Band 20 for its domestic 4G in the same way; an EE SIM placed on a Band 20-only single-band unit would see no EE layer inside the cab. The CVCD's dual-band chassis keeps Band 3 live alongside Band 20 so one box serves an EE driver and an O2 passenger at the same vehicle, which is the practical reason dual-band beats buying a single-band CVC for a mixed-carriage trip.

UK Network and MVNO Mapping: Which SIM Works on Which CVCD Band

The table below maps every SIM named on the CVCD product page to its host network and the band the booster repeats for it. Before ordering, check your SIM's host carrier rather than the shop brand, because the MVNO brand name itself does not appear on the tower.

A mixed-carriage family or crew benefits from different halves of the CVCD: the O2 work phone sees Band 20 light up, the EE personal phone sees Band 3 light up, and a shared vehicle where one passenger uses Giffgaff and another uses BT Mobile gets both bands boosted at once, which is the practical reason a dual-band chassis beats two single-band boxes inside one vehicle.

Gain and Output: >=45/50dB Gain Plus 10dBm Cabin Output

Gain, measured in decibels, is the factor by which the amplifier boosts the weak donor signal before re-radiating it; output power, also in decibel-milliwatts, is the transmit level the whip radiates inside the cab. The CVCD carries both: >=45 dB uplink and >=50 dB downlink gain recover a faint roadside donor, while 10 dBm spreads the recovered field across the seats. The 5 dB gap between uplink and downlink gain is normal because a tower transmits with high power and a phone transmits at low battery power.

Why gain listens and output fills the cabin

The steel roof, tinted glass and body shell hide the donor from a handheld phone; the >=45/50 dB gain lifts that hidden signal back above the decode floor, and the 10 dBm output carries it to the driver, co-driver and rear bench. This is a low-power in-vehicle class, not a building repeater: the modest output keeps radiation modest inside the cabin and stays inside the licence-exempt vehicle standard, while the gain does the recovery work.

Noise figure <=5 dB at 15 sessions

A perfect amplifier adds no noise; every real amplifier adds some, measured as the noise figure. The CVCD's noise figure of no more than 5 dB keeps added noise low enough that the amplified signal decodes cleanly rather than arriving louder but garbled, which matters when several family members or colleagues share the trip. A high noise figure would raise the indoor noise floor, cause the phone to select a louder but noisier cell, and reduce the usable uplink; a <=5 dB figure is the standard repeater quality level.

Automatic gain control on a moving donor

The automatic gain control balances recovered donor signal against the 10 dBm output as the vehicle moves between masts, backing off when a tower looms close and recovering when the donor fades between villages. This keeps the chassis stable rather than swinging between full output and silence, but it cannot remove the handover itself, which the phone and network still manage.

Why the CVCD Beats the Single-Band CVC and the CVGD Band 8+3

The vehicle range splits by tuned band, and choosing the wrong one leaves a whole network family absent inside the cab.

CVC: Band 20 alone for O2, Vodafone and Three

The CVC reaches O2, Vodafone and Three 4G on Band 20 alone and suits a driver whose phone rides one of those networks, but it leaves the EE Band 3 layer and the EE 2G path absent. An EE passenger inside the same cab sees no improvement from a CVC.

CVGD: Band 8 plus Band 3 for 2G and EE

The CVGD repeats all 2G voice on Band 8 plus EE 4G on Band 3, but it never tunes Band 20, so O2, Vodafone and Three 4G receive no boost at all even though they are the dominant rural-route layer.

CVCD: the only vehicle unit carrying both modern 4G families

The CVCD keeps Band 20 and Band 3 in one chassis, so it is the only vehicle unit in this comparison that serves every UK 4G network family plus EE circuit calls, which matters for a mixed-carriage family, a work van carrying different SIMs, or a caravan touring areas served by different masts.

Vehicle Signal Fluctuation: Why Bars Move Even After Amplification

A vehicle repeater improves the signal available inside the cab; it does not make the donor stop changing. Understanding the difference prevents an unfair expectation on a rural route.

Handover between masts

As the vehicle moves, the phone hands over from one macro cell to the next, and each handover causes a brief dip the network manages rather than the booster. The CVCD repeats whichever donor cell the roof antenna currently receives, so the bar count still rises and falls across a hill or a cutting; the gap between masts becomes usable instead of dropping to zero, but it never holds a perfect flat line at highway speed.

Stationary AGC settling

Parked at a campsite or layby, the automatic gain control locks onto the nearest cell and settles to a steady green LED within 3 to 5 minutes; this is where the cabin signal feels strongest. On the move, the AGC keeps balancing as the donor changes, which is normal and not a fault.

Obstacles: hills, cuttings, forest, tunnels

A solid hill, a railway cutting, dense forest or a tunnel blocks the donor regardless of amplification; the gain recovers a faint but present roadside signal, it does not see through solid terrain. Expect a dip entering a cutting and a return of bars on the open side, rather than a dead-free route everywhere.

Ofcom Licence-Exempt Status, UKCA, CE and RoHS Explained

Four marks sit on the CVCD: Ofcom licence-exempt status, UKCA for the UK market, CE for European conformity, and RoHS for restricted hazardous substances. Each answers a different regulatory question, and none changes the tuned bands, the >=45/50 dB gain or the 10 dBm output figure.

Ofcom licence-exempt and the vehicle output class

Ofcom's permitted-class rules allow a low-power mobile repeater on licensed mobile bands without the owner holding a spectrum licence. The CVCD meets the output, isolation and installation conditions of that class, so no application, fee, annual renewal or registration number is required, provided the unit is used as supplied, the antenna separation is respected, and it is not modified to raise output. The 10 dBm figure is the model's rated low-power output inside this class; the automatic gain control keeps the field balanced rather than running open-loop.

UKCA, CE and RoHS

UKCA confirms the product meets the applicable UK safety, electromagnetic compatibility and radio-equipment requirements for sale in Great Britain after the CE transition, the UK-market conformity declaration appearing on units supplied to UK customers. CE confirms conformity with the European Union Radio Equipment Directive and related health and safety standards, which is why the same kit ships across the EU delivery list including Germany, France, Italy, Spain, the Netherlands, Belgium, Austria, Sweden, Denmark, Finland, Ireland, Portugal, Poland and the Czech Republic as well as the UK. RoHS restricts lead, mercury, cadmium and other hazardous substances in electronics, so the chassis, cable and adapter comply with waste-electrical rules rather than containing banned materials. None of these marks alters how the bands repeat; they confirm the unit may be sold and used without a separate permit.

VoLTE and 2G Voice: How Calls Stay Connected in the Cab

Modern phones place calls over the 4G data layer using Voice over LTE (VoLTE), while older handsets and areas without VoLTE fall back to circuit-switched 2G GSM. The CVCD supports both routes where the network offers them, but its support differs by band.

VoLTE on Band 20 for O2, Vodafone and Three

Where the host network has enabled VoLTE on Band 20, a modern O2, Vodafone or Three handset places the call inside the boosted 800 MHz LTE session and the CVCD repeats that session like any other data call. The booster does not negotiate VoLTE itself; the phone and network do, and the unit simply carries the already established 4G call across the cabin where the 10 dBm output reaches.

2G circuit-switched voice on Band 3 for EE

EE maintains a 2G layer in the 1800 MHz region, and the CVCD's Band 3 path repeats circuit-switched voice and SMS for EE, ASDA, BT, Orange, T-Mobile, The People's Operator and Virgin handsets that cannot or do not use VoLTE. A basic feature phone, a passenger's handset, or a phone in a VoLTE-not-yet-enabled area still rings and completes a normal call over the boosted 2G layer.

What the CVCD does not carry for calls

The unit does not tune 3G Band 1 at 2100 MHz, so a network that still routes voice or data fallback through 3G on your route receives no boost on that layer. Where VoLTE is unavailable and the network relies on 3G circuit fallback, a call may not complete inside the vehicle even though 4G data shows bars; checking VoLTE support on your handset before ordering avoids that surprise, and neither gain nor output can invent a band the chassis does not tune.

Honest Limitations: No 3G Band 1, No 5G, and Cabin-Sized Coverage

A guide that lists only benefits misleads a buyer. The CVCD has three clear limits that should match your situation before you order, and neither the >=45/50 dB gain nor the 10 dBm output removes any of them.

No 3G Band 1 at 2100 MHz

The CVCD tunes only Band 20 and Band 3. It does not repeat Band 1 at 2100 MHz, the 3G UMTS layer some networks still use for data fallback or circuit-switched voice. A route that relies on 3G where 4G fails will see that fallback unboosted inside the cab; raising gain cannot manufacture a band the hardware never receives, and this is the single most important technical limit for areas already served only by Band 20 or Band 3 4G rather than 3G-only locations.

No 5G on any band

The CVCD does not tune n78 (3.5 GHz), n8 (900 MHz) or any other 5G band, and it does not convert 4G into 5G. A 5G phone still receives its normal unboosted 5G signal from the macro tower, and the CVCD only lifts the 4G Band 20 plus Band 3 layers. Expect reliable 4G calls and data across the cabin, not boosted 5G speeds, no matter how high the gain.

Cabin and small caravan interior only, ~100 m2

The rated space is the vehicle cabin or a small caravan interior, roughly 100 m2, supporting up to 15 active sessions. It is not a building repeater for a house, office or large warehouse, and it will not blanket an open field or a farmyard; a permanently sited space clearly beyond the cabin limit needs a building-rated unit rather than more vehicle output. The 15-user count means active calls and data sessions inside the vehicle, not every registered device on the premises.

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