Answer first: the CD500 is a dual-band FDD LTE 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 >=60 dB uplink and >=65 dB downlink gain lift weak donor cells, while its >=20 dBm output power is the flagship step above the CD250's >=17 dBm and the CD200's >=10 dBm, doubling reach over the CD250 to fill 500 m2 and support 50 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 should not be stretched beyond 500 m2.

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-building 4G layer. Inside a large home or business, Band 20 is the band that reaches the upper floor, the far office wing, the annex and the garden room where the higher-capacity band fades.

Uplink and downlink frequency pairs for Band 20

A 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 CD500 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 indoors.

Why 800 MHz reaches the far wing but carries less capacity

Lower frequency propagates farther and passes walls with less loss, but each MHz block carries fewer simultaneous data sessions than the higher bands. Band 20 is therefore the coverage band: it keeps a phone connected at the edge of the property, while EE's Band 3 carries the capacity where many devices gather. A rural Devon cottage, a Yorkshire home or a Wales office on O2, Vodafone or Three relies on Band 20 being repeated indoors; the CD500 does that on the donor side before the >=20 dBm output spreads it inside.

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 brick, double-glazing and floor slabs, which is why it reads weaker deep inside a building even in a well-covered city.

Uplink and downlink frequency pairs for Band 3

The CD500 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, an elderly relative'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.

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 indoors. The CD500's dual-band chassis keeps Band 3 live alongside Band 20 so one box serves an EE household and an O2 visitor at the same large address, which is the practical reason dual-band beats buying a single-band C500 for a mixed-network home or business.

UK Network and MVNO Mapping: Which SIM Works on Which CD500 Band

The table below maps every SIM named on the CD500 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-carrier office or family benefits from different halves of the CD500: the O2 household sees Band 20 light up, the EE household sees Band 3 light up, and a shared building where one person 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 across a 500 m2 property.

Gain Explained: >=60 dB Uplink and >=65 dB Downlink on Both Bands

Gain, measured in decibels, is the factor by which the amplifier boosts the weak donor signal before re-radiating it. The CD500's >=60 dB uplink gain and >=65 dB downlink gain are asymmetric: a tower transmits with high power while a phone transmits at low power from a battery, so the uplink path loses more energy on the way back and the amplifier still only needs to restore the faint phone signal to a level the tower can decode. The 5 dB gap between the two figures is normal for a home repeater and not a defect.

How the 65 dB downlink margin buys walls and floor loss

Every indoor surface costs signal: a plasterboard partition costs a few dB, an external brick wall costs 10 to 20 dB, a store or kitchen wall with appliances costs more, a ceiling slab between two floors adds its own loss, and metal warehouse shelving or a bar counter adds attenuation on top. The >=65 dB downlink margin absorbs that cumulative loss so the phone still shows bars in the upper floor, the far office wing and the annex, where a smaller unit's thinner margin runs dry.

Noise figure <=5 dB and why it matters at 50 sessions

A perfect amplifier adds no noise; every real amplifier adds some, measured as the noise figure. The CD500's noise figure of no more than 5 dB keeps that added noise low enough that the amplified signal still decodes cleanly rather than arriving louder but garbled, which matters more at 50 concurrent sessions than at a handful of phones. 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.

Gain is not the same as output power

Gain describes amplification factor; output power, covered next, describes the absolute ceiling the repeater may transmit at from its indoor antenna. A unit can have high gain yet still keep output controlled, because the automatic gain control raises gain only until a stable indoor signal appears and then backs off rather than running at maximum all the time. The CD500 reaches farther through structure not by over-amplifying, but by combining steady gain with a higher output budget.

Why >=20 dBm Output Is the CD500 Flagship: vs CD250 >=17 and CD200 >=10

Maximum output power, listed as >=20 dBm on the CD500 spec, is the ceiling the repeater may radiate from its indoor antenna. The CD200 sits at >=10 dBm, the CD250 at >=17 dBm, and the CD500 raises that output to >=20 dBm while keeping the same >=60/65 dB gain as the CD250. The 3 dB step from 17 to 20 dBm represents roughly twice the radiated power delivered to the indoor whip after cable and wall losses; the 10 dB step from 10 to 20 dBm represents ten times the power compared with the CD200 class.

What 20 dBm of radiated power means in practice

Output power sets how loud the indoor field reaches past partitions, a solid bar counter, a warehouse racking row or a linked office wing. The CD250's >=17 dBm fills 250 m2; the CD500's >=20 dBm keeps the same good listening and roughly doubles the final loudness, pushing the field an extra 250 m2 across the larger footprint and from 25 to 50 sessions. The extra output buys reach through structure, not louder distortion, because the <=5 dB noise figure and automatic gain control keep the field clean.

More amplification does not mean more transmitted watts

More gain inside the box does not force the indoor donor farther past the regulations; the automatic gain control balances the two so a 65 dB stage still ends at the controlled >=20 dBm ceiling rather than blowing past it. A weak donor needs a better-aimed aerial position, not a higher output that the unit already holds in reserve.

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

Four marks sit on the CD500: 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 or the >=20 dBm output figure.

Ofcom licence-exempt

Ofcom's permitted-class rules allow a low-power indoor repeater on licensed mobile bands without the owner holding a spectrum licence. The CD500 meets the output and isolation conditions of that class, so no application, fee, annual renewal or registration number is required, provided the unit is used as supplied, kept separated from its own donor antenna, and not modified to raise output. The higher >=20 dBm figure sits inside this class because the automatic gain control caps the radiated field; the owner still must use the unit as supplied and keep separation.

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 Across 500 m2

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 CD500 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 CD500 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 large building where the >=20 dBm margin reaches.

2G circuit-switched voice on Band 3 for EE

EE maintains a 2G layer in the 1800 MHz region, and the CD500'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, an elderly relative'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 CD500 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 in your location receives no boost on that layer. Where VoLTE is unavailable and the network relies on 3G circuit fallback, a call may not complete indoors even though 4G data shows bars; checking VoLTE support on your handset before ordering avoids that surprise, and the higher output cannot invent a band the chassis does not tune.

Honest Limitations: No 3G Band 1, No 5G, and Only 500 m2

A guide that lists only benefits misleads a buyer. The CD500 has three clear limits that should match your situation before you order, and neither the >=20 dBm output nor the >=60/65 dB gain removes any of them.

No 3G Band 1 at 2100 MHz

The CD500 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 home that relies on 3G where 4G fails will see that fallback unboosted indoors; raising output to 20 dBm 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 CD500 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 CD500 only lifts the 4G Band 20 plus Band 3 layers. Expect reliable 4G calls and data across 500 m2, not boosted 5G speeds, no matter how high the output or gain.

Only 500 m2 for 50 simultaneous users

The rated footprint of 500 m2 (5,382 ft2) fits a detached family home, a large office, a retail floor, a pub, a cafe or a warehouse, and supports up to 50 active sessions. A large estate over multiple separate buildings, a factory floor clearly beyond 500 m2, or a multi-block campus needs a larger unit or a second unit rather than more output from this chassis. The 50-user count means active calls and data sessions, not every registered device in the building, and beyond that ceiling the network itself schedules phones.

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