Answer first: the CG500 is the Boost4U 500 m² Band 20+8 flagship repeater: it lifts O2, Vodafone and Three 4G data through the 800 MHz layer, keeps O2 and Vodafone ordinary 2G voice calls and SMS alive through the 900 MHz layer, with ≥60 dB uplink and ≥65 dB downlink gain, a ≥20 dBm licence-exempt output about twice the power of a 17 dBm unit, a ≤5 dB noise figure, 500 m² of indoor space and 50 simultaneous sessions, and an included high-gain Yagi for weak rural donors. It suits the O2 and Vodafone detached home, medium office or small hotel that loses both data and calls inside stone or render; it does not repeat EE 2G voice on Band 3 at 1800 MHz, does not carry 3G Band 1, does not carry 5G, and stays rated for 500 m² rather than a multi-building estate.

Band 20 (800 MHz): The Long-Range 4G Layer for O2, Vodafone and Three

Band 20 occupies the 800 MHz spectrum Ofcom freed up after the analogue TV switch-off. Its longer wavelength travels farther from the macro mast, bends around hills and hedgerows, and penetrates brick better than the higher-capacity bands, which is why O2, Vodafone and Three deployed it as the rural and deep-road 4G layer. On a village lane, Band 20 is the layer that keeps a data session alive between masts where higher bands fade.

Paired transmit and receive frequency blocks for Band 20

A home repeater works on a paired FDD block: the phone transmits on one block and receives on another, and the amplifier repeats both directions without mixing them. The CG500 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 4G reply amplified across all floors of the 500 m² property, with the included Yagi aimed at the single rural mast when the donor is faint.

Why 800 MHz reaches the far mast but carries less capacity

Lower frequency propagates farther and passes a stone wall or hillside with less loss, but each MHz block carries fewer simultaneous data sessions than the higher bands. Band 20 is therefore the coverage band in the countryside: it keeps a phone connected at the edge of the mast range, while denser town capacity lives on other layers the CG500 does not tune. A Three user in Scotland, an O2 giffgaff home office in Cornwall, or a Vodafone Lebara household relies on Band 20 being repeated inside; the CG500 does that on the donor side before the ≥65 dB gain and ≥20 dBm output spread it across the zones.

Band 8 (900 MHz): The O2 and Vodafone 2G Voice and SMS Layer

Band 8 sits at 900 MHz, the original GSM cellular band O2 and Vodafone maintain for circuit-switched 2G voice calls and SMS where VoLTE or 3G fallback is unavailable. Its wavelength passes internal stone and rendered walls more cheaply than 1800 or 2600 MHz, which is why an ordinary call often rings indoors even when the 4G bar count looks thin.

Paired transmit and receive frequency blocks for Band 8

The CG500 repeats the 890 to 915 MHz uplink and the 935 to 960 MHz downlink so an O2 or Vodafone handset places and receives a normal circuit call inside the property even where the 4G data layer is weak. This is the feature that separates CG500 from a Band 20-only box: data alone does not keep a dropped call fixed, and field reports describe O2 calls in Yorkshire stopping dropping once the chassis carried the voice layer.

Why 900MHz survives rendered walls where a higher data layer fades

Band 8 at 900 MHz and Band 20 at 800 MHz sit close, but the 900 MHz GSM layer has decades of indoor building penetration behind it, travels through solid stone and rendered walls with modest loss, and remains the circuit layer older phones dial on. In a shared office or small hotel where many handsets ring at once, that wall-penetrating call layer matters as much as the data session; the 800 MHz Band 20 carries data over distance on the mast route, the 900 MHz Band 8 keeps the call legible inside, and the flagship chassis runs both at once.

The Unique Band 20 + 8 Combo: 4G Data and Voice From One Flagship Box

Across the Boost4U home range, Band 20 repeats 4G data and Band 8 repeats 2G voice, and combining them in one chassis is the Band 20+8 defining placement. A Band 20-only unit keeps data but drops the call when VoLTE is unavailable; a Band 8-only unit keeps the call but never accelerates the data session. The CG500 keeps both across 500 m², which matches the O2 and Vodafone detached home or small business that complains of both slow internet and dropped calls across many rooms.

UK Network and MVNO Mapping: Which SIM Rides Which Band

The table below maps every SIM named on the CG500 product page to its host network and the band the booster repeats for it. Before ordering, check the SIM's host carrier rather than the shop brand, because the MVNO name itself does not appear on the tower.

An O2 giffgaff home-office phone sees both bands light up, a Vodafone Lebara handset keeps its circuit call on Band 8, and a Three data-only session rides Band 20 without a Band 8 call path. In a mixed household or small business on two networks, different members benefit from different halves of the chassis, which is the practical reason a dual-band flagship beats a single-band purchase.

Gain, Output and the +3dB Flagship Step: ≥60/≥65dB Gain Plus ≥20dBm Output

Gain, measured in decibels, is the factor by which the amplifier lifts the weak donor signal before re-radiating it; output power, in decibel-milliwatts, is the transmit level the indoor whip or split branches radiate into the room. The CG500 carries both: ≥60 dB uplink and ≥65 dB downlink gain recover a faint rural donor, while ≥20 dBm spreads the recovered field across 500 m² for 50 sessions.

What +3dB over a 17dBm unit means in real power

Decibels are logarithmic: a +3 dB step roughly doubles radiated power, so +3 dB from 17 dBm to 20 dBm equals about twice the transmit level. That extra output is the CG500's flagship differentiator over the CG250, and it matters specifically when the field divides through a splitter to a second or third indoor antenna or when 50 handsets share one building: each branch and each active session costs a little headroom, and the 20 dBm level absorbs that load so all three whips still hold a usable field rather than fading after one branch.

Why 60/65dB gain still pairs with a fixed licence-exempt output

The ≥60/65 dB gain sits in the recovery stage that listens for the faint rooftop donor; the ≥20 dBm output stays fixed inside Ofcom's permitted class and does not rise with gain. Raising gain does not raise output past the limit, and the automatic gain control balances recovered donor against the fixed output as weather and daytime traffic change, backing off when a tower looms close and recovering when the donor fades behind a cloud or ridge.

Noise figure ≤5dB across 50 shared sessions

A perfect amplifier adds no noise; every real amplifier adds some, measured as the noise figure. The CG500's ≤5 dB figure keeps added noise low enough that the amplified signal decodes cleanly rather than arriving louder but garbled, which matters when fifty family members, staff or guests share the building. A high noise figure raises the indoor floor, causes the phone to select a louder but noisier cell, and reduces usable uplink; a ≤5 dB figure is the standard repeater quality level.

Dual-Band CG500 vs Single-Band C100, the CG250 and the CD500

The home range splits by tuned band, rated size and output, and choosing the wrong one leaves a whole service, a whole wing or a whole branch absent indoors.

C100: Band 20 alone for data, no circuit call path

The C100 reaches O2, Vodafone and Three 4G on Band 20 alone and suits a data-only household whose calls already ride VoLTE, but it leaves the Band 8 voice layer absent; an older O2 handset without VoLTE sees no boosted call even though data improves, and it cannot serve a 50-user building at all.

CG250 to CG500: same bands, double the area, users and output

The CG500 keeps the identical Band 20+8 combo and the same ≥60/65 dB gain as the CG250 but adds 250 m² of coverage, 25 users, a +3 dB output rising to 20 dBm, a third indoor antenna through the splitter, and the Yagi included instead of paid. Pick CG250 for a 250 m² home with one whip and CG500 for a 500 m² detached house or small business; neither changes which services are carried.

CD500: Band 20 + Band 3 for EE voice, not O2/Vodafone calls

The CD500 repeats Band 20 4G plus Band 3 at 1800 MHz for EE 2G voice on the same 500 m² and 50-user rating, but leaves the O2/Vodafone Band 8 circuit call unboosted. The two units share size, output and the included Yagi but solve opposite voice problems: CG500 for an O2/Vodafone household, CD500 for an EE household.

VoLTE and the Band 8 Circuit Fallback

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 CG500 supports both routes where the network offers them, but its support differs by band.

VoLTE on Band 20 for O2 and Vodafone

Where O2 or Vodafone has enabled VoLTE on Band 20, a modern handset places the call inside the boosted 800 MHz LTE session, and the CG500 repeats that session like any other data call. The booster does not negotiate VoLTE itself; the phone and network do, and the unit carries the already established 4G call across the building where the ≥20 dBm output reaches.

Band 8 2G fallback where VoLTE is unavailable in a rural village

Where VoLTE is switched off or the phone is older, the call returns to the Band 8 900 MHz circuit layer on 890–915 MHz uplink and 935–960 MHz downlink, which the CG500 repeats for O2 and Vodafone. In a village with VoLTE not yet enabled, a basic feature phone or guest's handset still rings and completes a normal call over the boosted 2G layer rather than dropping to no service indoors, and the 900 MHz path survives the rendered wall that weakens the 4G session.

What the CG500 does not carry for calls

The unit does not tune 3G Band 1 at 2100 MHz, so a network that still routes voice fallback through 3G on your street receives no boost on that layer. Where VoLTE is off and the network relies on 3G circuit fallback rather than Band 8, a call may not complete inside even though 4G data shows bars; checking VoLTE support on the handset before ordering avoids that surprise, and neither gain nor output can invent a band the chassis does not tune.

Ofcom Licence-Exempt Status, UKCA, CE and RoHS Alongside the 20dBm Output

Four marks sit on the CG500: 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 ≥60/65 dB gain or the ≥20 dBm output figure.

Ofcom licence-exempt and the permitted output class

Ofcom's permitted-class rules allow a low-power fixed repeater on licensed mobile bands without the owner holding a spectrum licence. The CG500 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 10 m antenna separation is respected, and it is not modified to raise output. The ≥20 dBm figure sits inside this class rather than above it; the automatic gain control keeps the field balanced, and the flagship output compared with a 17 dBm unit is still a permitted fixed level, not an unlocked amplifier.

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. 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, cables and adapter comply with waste-electrical rules. None of these marks alters how the bands repeat; they confirm the unit may be sold and used without a separate permit.

Honest Limitations: No 3G Band 1, No 5G, EE Voice Not Carried, 500m² Only

A guide that lists only benefits misleads a buyer. The CG500 has four clear limits that should match your situation before you order, and neither the ≥60/65 dB gain nor the ≥20 dBm output removes any of them.

No 3G Band 1 at 2100 MHz

The CG500 tunes only Band 20 and Band 8. 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 street that relies on 3G where 4G fails sees that fallback unboosted indoors; raising output cannot manufacture a band the hardware never receives.

No 5G on any band

The CG500 does not tune n78 (3.5 GHz), n8 (900 MHz 5G) 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 CG500 only lifts the 4G Band 20 data layer plus the Band 8 voice layer. Expect reliable 4G calls and data across 500 m², not boosted 5G speeds, no matter how high the output.

EE 2G voice is not carried; 500m² ceiling

EE runs its 2G voice on Band 3 at 1800 MHz, which the CG500 does not tune, so an EE household gets 4G data where reach applies but not a boosted EE circuit call; that gap belongs to the CD500. The rated space is 500 m² for a detached home, medium office or small hotel supporting 50 sessions; it is not a multi-building or estate system, and it will not blanket a separate farmyard, outbuilding or annex beyond the main roof. A permanently sited multi-building space clearly beyond 500 m² needs a commercial array rather than more home output.

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