@Dollhouse12345 You can cancel your contract online.

https://info.o2online.de/kuendigung/

For sending back an o2 rented router please use the router return portal. Keep the DHL receipt.

https://router-retoure.o2online.de/start/app/dashboard

https://info.o2online.de/kuendigung/

If you wish to cancel before the end of the minimum contract term, please state this correctly and enclose the necessary documents. 

A deposit cannot be refunded as you have not paid a deposit.
Please note that you will be charged the value of the router if you do not return a loaner/rental device. 

Please use the o2 returns portal to return a loan or rental device. 

Thank you for your answers. Do I need to attach the abmeldung from the city to confirm the exit? And by when should the devices be sent to the O2 address? 

If it is a contract with an unexpired minimum contract term, to terminate the contract prematurely you must provide proof of your move abroad in the form of deregistration from the registration office in Germany and registration with the registration office abroad or comparable proof. 

A loaned or rented device must be returned at the end of the contract in accordance with the o2 General Terms and Conditions. Please note that the DHL return label from the o2 return portal can only be used within Germany. 

Hello @Dollhouse12345, 

great that you have already received strong support from Joe Doe and blablup 

As already mentioned, the confirmation of deregistration from the residents' registration office in Germany is required as proof for the special termination when moving abroad.

A rented router should be returned to us promptly after the end of the contract. You can do this via our return portal.

Best regards 
Cora