The CD500 covers 500 m² for 50 users at ≥60/≥65 dB gain and ≥20 dBm output with up to 3 indoor antennas; the CD1000 doubles the space and users to 1000 m² / 100 users by raising gain to ≥70 dB uplink and ≥75 dB downlink (about +10 dB, ≈10× amplification), keeps the same Ofcom-cap ≥20 dBm output, and supports up to 4 indoor antennas. The C1000 is a single Band 20 (800 MHz) unit for O2/Vodafone-only over 1000 m² at roughly 17 dBm, missing EE Band 3 4G and voice. Choose the CD1000 for a commercial site where weak donor signal, large area and all four operators matter; step down to the CD500 for 500 m², and choose the C1000 only if you are O2/Vodafone-only without EE.

Band 20 (800 MHz) is the rural propagation band used by O2 and Vodafone for 4G, reaching farther over distance and through obstacles; Three 4G rides Band 20 over the shared O2 MOCN. Band 3 (1800 MHz) carries EE 4G alongside the EE 2G GSM layer for calls and SMS. The CD1000 amplifies both simultaneously, so an O2 staff phone and an EE customer phone in the same building both get boosted 4G without switching boxes.

Up to 1000 m² (10,764 ft²) means a large open-plan office or retail shop, a multi-floor pub/café, a hotel or guest house, a warehouse/factory unit, or a large rural farm house/estate. It is not a multi-site campus or a whole very large distribution hall; beyond 1000 m² a distributed multi-antenna system is needed. Steel cladding, thick concrete and distance from the antenna shrink the usable area.

The CD1000 supports up to 100 phones or data devices connected at the same time, sharing the boosted Band 20 and Band 3 capacity. This suits a large office, a busy hotel or a warehouse with mixed-carrier staff and customer devices. Beyond 100 active users the shared RF capacity thins out; a full multi-floor company or a very large logistics hall needs a higher-capacity distributed system. It is connected capacity, not a guaranteed 100 fast-speed lines at once.

Gain in dB measures how much the amplifier strengthens the signal: ≥70 dB uplink lifts your phone's signal back up to the mast, and ≥75 dB downlink lifts the mast's signal down to your phone. That is +10 dB over the 60/65 dB class, about 10× more amplification, which is what reaches farther through stone, concrete and metal and rescues weak fringe donor signal. Output in dBm measures the final radiated strength: ≥20 dBm ≈100 mW stays at the Ofcom cap. High gain and a capped output work together — gain digests a weak donor; output re-broadcasts it inside.

UK Ofcom licence-exempt repeaters are capped at ≥20 dBm output; a unit cannot legally radiate more. The CD1000 therefore gains coverage from more amplification (70/75 dB) rather than higher radiated power. Higher gain lifts a very weak incoming donor signal that a lower-gain unit would simply pass on as noise, and that is why it suits weak-signal rural and commercial sites; the same ≥20 dBm cap applies to every licence-exempt CD unit.

The supplied 5 dBi omni works well with a clear mounting spot showing 1–2 bars when you do not need to aim at a specific mast. Where donor signal is very weak, or the mast lies in one direction behind a ridge or other buildings, a high-gain directional focus on that mast often makes the difference between marginal and solid; the high CD1000 gain then amplifies a cleaner incoming signal. Start with the omni, read the bar count, and add directional focus only if signal stays weak.

At least 1–2 bars of usable outdoor signal on Band 20 and/or Band 3 at the omni mounting point, checked with a phone outside on the wall, roof or eave. A booster amplifies the donor signal it receives; it cannot create signal where none exists outside. Multi-antenna expansion needs a stronger donor still. If your phone shows zero bars and emergency calls only even at the mounting point, this unit will not work, and neither will any Ofcom-legal booster at this level.

The CD1000 carries a 365-day money-back guarantee: if it does not work for your location, return it by mail within 365 days for a refund; return shipping is deducted from the refund (ReturnShippingFees), so it is not a free-return label. Standard delivery is free: handling takes 1–2 working days and UK transit 10–15 working days, so it is not next-day, and the same policy covers 15 European countries (GB, DE, FR, IT, ES, NL, BE, AT, SE, DK, FI, IE, PT, PL, CZ).

The CD1000 boosts 4G LTE data and 2G calls/SMS; calls over 4G work when your handset and network offer VoLTE (Voice over LTE), which O2, Vodafone, EE and Three support on compatible plans. It does not boost 5G NR on any band and it does not boost 3G UMTS Band 1 (2100 MHz), so a device stuck on 3G fallback will not be helped. If 5G speed or 3G fallback is the main requirement, a different unit on those bands is needed.