Invoice and contract summary

Then you need to register your contract using the telephone number.

 Of course I have registered using my email and telephone number.

Can you try it from different Browser? 

I actually did. And I am trying this everywhere since yesterday. 

Hello ​@MrBlackR,

welcome to our o2 Community 😀

If you cannot view your contract in the customer portal, it means you haven't logged in with your contract details. Instead, you have created a prospective customer account (for non-customers).

Did you already register your contract there: Registrierung auf Mein o2?

What type of contract is it (prepaid, mobile plan, landline, or hardware)?

Best regards

Giulia

I have bought a handy in installments yesterday. I have gotten the order confirmation. And I also paid the one time fee. 

With one-time fee you mean a down payment? You need to wait until you receive a contract number, then use that to register. The invoice won't be available until the phone has been sent.

Ohh thank you then. This is what I wanted to know. :)