Let's say I want to sell my Huawei P20 that I originally bought with a contract with Mobilcom Debitel. Can I just sell the phone to somebody and somehow transfer the warranty rights to him or is that not possible? And can I then put my sim card in another cell phone and continue to use my flat?
Of course you can sell your mobile phone, the warranty goes with the buyer and your sim can be used in any mobile phone.
Yes, and they do just about everything. You just have to give him the bill.
Have heard that there can be problems because some providers only provide the warranty for first-time buyers…
Guarantees are usually transferred with the sale (so the guarantee is not extinguished), because they are coupled to the respective device. As a proof of the purchase date then usually a bill, so the device can't be accurately determined by the serial number. With mobile phones you will always need an invoice.
I've never heard, but I do not know 100%
