Does the Cat B35 work on O2 (Telefónica)?

Q: Does the Cat B35 work on O2 (Telefónica)?

Works with caveats. Calls and texts can fall back to 2G. O2 switches 2G off in the second half of 2028 and asks people to replace 2G-only devices by 1 July 2028. We haven't found confirmation that 4G Calling works on O2 (Telefónica). 4G data should work (shared bands: 1, 3, 7, 8, 20).

Last checked 23 Oct 20265 sourcesWorked out from published specs

It works, with caveats.

Works with caveats

Calls and texts can fall back to 2G. O2 switches 2G off in the second half of 2028 and asks people to replace 2G-only devices by 1 July 2028. We haven't found confirmation that 4G Calling works on O2 (Telefónica). 4G data should work (shared bands: 1, 3, 7, 8, 20).

Fine for now. The catch is how calls get through: if they ride on 2G or 3G, they stop when O2 (Telefónica) switches that off.

We worked this out from the phone's published bands and O2 (Telefónica)'s own published network facts (see How we check). Nobody has confirmed it for this exact pairing yet.

O2 (Telefónica) (Germany)

3G: Switched off in 2021
2G: On until the second half of 2028 (replace 2G-only devices by 1 July 2028)

Cat B35

2G: GSM 850 / 900 / 1800 / 1900
3G: Not published or not checked yet
4G bands: 1, 3, 7, 8, 20
4G Calling: unknown – No network or maker VoLTE confirmation found.

Other networks in Germany

Telekom Works with caveats
Vodafone Works with caveats
1&1 Works with caveats

Everything about the Cat B35 · All phones on O2 (Telefónica) · Dumbphones that work in Germany

Using a Cat B35 on O2 (Telefónica)? Tell us how it went and we'll update this page. Report your result.

Sources

How we decide: our method.