The six brands below own no masts. Each rents signal wholesale from one of the big four, strips out shops and frills, and sells the identical radio waves for less. The examiner's rule: check the landlord's coverage at your postcode, then buy from whichever tenant prices it best.
Tesco Mobile
Runs on: O2's masts. The supermarket operator with a long record for plain pricing and family-friendly service.
- Clubcard-linked pricing hooks
- Family SIM discounts
- O2's reach for less
- Long-standing customer-satisfaction record
- Perks lighter than the landlord's Priority
- Top-end 5G tiers arrive later than on O2 itself
giffgaff
Runs on: O2's masts. The no-shops, no-call-centre operator: everything runs online and through its community, on rolling monthly goodybags.
- No contracts at all — resize or leave monthly
- Strong value on mid-size bundles
- The cheapest honest audition of O2's masts
- No phone support — online help only
- Handset finance aside, everything is DIY
Sky Mobile
Runs on: O2's masts. The TV giant's operator — marked in full in its own report; listed here as the third O2 tenant.
- Data reserve banks leftovers for years
- Penalty-free monthly resizing
- Household perks inside Sky homes
- Inherits O2's evening squeeze
- eSIM and Wi-Fi Calling on the landlord's timetable
SMARTY
Runs on: Three's masts. Three's own in-house budget brand: rolling monthly plans, unused-data discounts on some tiers, zero frills.
- Three's full 5G pace for less
- Rolling monthly — the perfect audition SIM
- Simple, honest plan grid
- Same deep-indoor weaknesses as the landlord
- No shops; support is online-first
iD Mobile
Runs on: Three's masts. The electronics-retailer brand on Three's signal, with aggressive bundle pricing.
- Frequently the cheapest per-GB on Three's radio
- Rollover on some tiers
- eSIM support arrived across recent plans
- Service satisfaction has trailed the leaders
- Same landlord weak spots indoors
VOXI & Lebara
Runs on: Vodafone's masts. Two tenants of the fourth landlord: VOXI aims young with endless-social tiers; Lebara leads on international minutes.
- VOXI: social apps that don't touch the allowance
- Lebara: strong international-calling bundles
- Vodafone reach at budget prices
- Different landlord than the four reviewed here — run the Vodafone coverage check first
- Perk lists change; verify the current inclusion grid
1pMobile
Runs on: EE's masts. The pay-per-use minnow on the champion's signal — charging by the unit, suiting genuinely light users.
- EE's broadest-in-Britain reach for pennies
- No monthly commitment at all
- The cheapest possible audition of EE's masts
- Heavy users overspend fast on per-unit rates
- Minimal extras by design
- Identify the landlord (host network) first — it decides your actual signal.
- Run that landlord's coverage checker plus Ofcom's at your postcode, weighting indoor readings.
- Audition one rolling month before any fixed term.
- Remember support and features (eSIM, Wi-Fi Calling) follow the tenant's timetable, not the landlord's.