All 4 UK networks vs one
Fuse data uses all four UK networks (EE, Vodafone, Three, O2) automatically. SMARTY is a sub-brand of Three — your coverage depends entirely on Three wherever you are.
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Fuse vs SMARTY
Fuse Mobile and SMARTY are both eSIM options in the UK. The difference is network reach: Fuse uses all four UK networks with automatic switching to the strongest; SMARTY is a sub-brand of Three and runs on Three's network only. Here's the comparison — all SMARTY facts verified from smarty.co.uk on 4 June 2026.
| Feature | Fuse | SMARTY |
|---|---|---|
| Product | UK multi-network data-only eSIM | UK mobile service on Three (sub-brand of Three) |
| UK networks | All 4 (EE, Vodafone, Three, O2) | Three only |
| Multi-network switching | ||
| Data — apps you can use | Any app, any service. Standard unrestricted data. | Any app, any service. Standard unrestricted data. |
| Banking, social, streaming, VPN, gaming | ||
| Starting price | From £5.99/mo for 5GB | From £6/mo for 5GB |
| International roaming | 130+ countries on Pulse and Surge | 48 EU/EEA destinations, 12GB/month cap |
| eSIM | ||
| Contract | Monthly rolling, cancel any time | Rolling 1-month, no minimum |
Product
FuseUK multi-network data-only eSIM
SMARTYUK mobile service on Three (sub-brand of Three)
UK networks
FuseAll 4 (EE, Vodafone, Three, O2)
SMARTYThree only
Multi-network switching
Fuse
SMARTY
Data — apps you can use
FuseAny app, any service. Standard unrestricted data.
SMARTYAny app, any service. Standard unrestricted data.
Banking, social, streaming, VPN, gaming
Fuse
SMARTY
Starting price
FuseFrom £5.99/mo for 5GB
SMARTYFrom £6/mo for 5GB
International roaming
Fuse130+ countries on Pulse and Surge
SMARTY48 EU/EEA destinations, 12GB/month cap
eSIM
Fuse
SMARTY
Contract
FuseMonthly rolling, cancel any time
SMARTYRolling 1-month, no minimum
SMARTY data in the table above was verified from SMARTY's own published pages on 4 June 2026. Pricing and promotional terms change frequently — please re-check SMARTY's website for current details before deciding.
Sources: All plans·About SMARTY (Three network)·Roaming·eSIM support·Price Guide V40 (Feb 2026)
Why Fuse
What Fuse offers.
Strongest signal wins
Fuse scans all four networks continuously and moves to whichever is strongest in under a second. With SMARTY you stay on Three — if Three is weak in your area, your data stays weak.
No weak-zone problem
Single-network providers have coverage maps with gaps. Fuse fills those gaps with the other three networks — when one weakens, another takes over before you notice.
Wider roaming reach
Fuse Pulse and Surge plans include data in 130+ countries. SMARTY covers 48 EU/EEA destinations with a 12GB/month roaming cap.
Fuse is a UK multi-network data-only eSIM — one digital SIM that uses all four UK networks (EE, Three, Vodafone, O2) and switches automatically to whichever has the strongest signal. Fuse does not issue a phone number; SMARTY does. Most customers keep SMARTY for calls and SMS on their existing number, and add Fuse alongside via dual-SIM to handle data.
Yes. Every eSIM-capable phone (most flagships from 2018 onwards) supports dual-SIM — one physical SIM and one eSIM, or two eSIMs. Keep SMARTY for calls and SMS, install Fuse as a second eSIM for data. Both lines work at the same time.
No. Fuse is data-only — there is no number, no carrier voice calls, no SMS. Apps like WhatsApp, FaceTime, iMessage and Signal work normally over the Fuse data line. Your existing SMARTY number stays where it is.
No — Fuse is rolling monthly. Cancel or change plan any month with no exit fees. Plans start at £5.99/month for Spark (5GB), £9.99 for Pulse (10GB plus roaming in 130+ countries), and £14.99 for Surge (15GB plus roaming).
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