Simple phones that work on Tesco Mobile

Tesco Mobile runs on O2's network.

2G: On. O2 plans to start switching off 2G in summer 2029.
4G calling for phones they didn't sell: Approved phones only. Tesco Mobile has a per-phone 4G calling checker.

Phone	Verdict	Why
HMD Fusion X1	Works	Calls and texts should work on Tesco Mobile, including over 4G.
Alcatel 3080G	Works	Calls and texts should work on Tesco Mobile, including over 4G.
HMD 105 4G	Works (on 2G)	Calls and texts work on Tesco Mobile using 2G. They'll stop working when 2G is switched off unless 4G calling gets enabled.
HMD 110 4G	Works (on 2G)	Calls and texts work on Tesco Mobile using 2G. They'll stop working when 2G is switched off unless 4G calling gets enabled.
HMD 2660 Flip 4G	Works (on 2G)	Calls and texts work on Tesco Mobile using 2G. They'll stop working when 2G is switched off unless 4G calling gets enabled.
HMD 3210 4G	Works (on 2G)	Calls and texts work on Tesco Mobile using 2G. They'll stop working when 2G is switched off unless 4G calling gets enabled.
Mudita Kompakt	Works (on 2G)	Calls and texts work on Tesco Mobile using 2G. They'll stop working when 2G is switched off unless 4G calling gets enabled.
Punkt MP02	Works (on 2G)	Calls and texts work on Tesco Mobile using 2G. They'll stop working when 2G is switched off unless 4G calling gets enabled.

Sources