Hello @gregor6464 ,

the easiest way to cancel your contract would be to use the online form for this. If you need further help with it or just have any other questions, please let us know.

Kind regards, Sven

Hi, 
In that form I need to fill rufnummer, where i can find this number?
Regards

Hello @gregor6464 ,

you should be able to find it in the contract documents that you got at the start of the contract, as well as on any bill as well as by just looking at the contract itself in your mein o2.

Kind regards, Sven