Beste antwoord door David
If I understand correctly, you want to switch to a subscription with a device, but don't have any of the valid identifications? With the Sim Only subscription you can choose to use Toestel Flexibiliteit. You can annul your current subscription and start a new contract with a new device. This is only possible if you have one of the fore-mentioned ID's. Keep in mind that other carriers might have the same regulations.
If this does not apply to you, you have some alternatives. You can't sell a contract, but we do provide the option to transfer a contract to another person. On this page you can find all the information, however this is in Dutch. I don't know how well you read Dutch, so we can always help you with it! You have to fill in this application, add a copy of your ID and a copy of the person who's taking over the contract and sent it to firstname.lastname@example.org. The costs for a transfer of a contract are € 25,42. The other alternatives are finishing your contract or buy off the remaining months.
Hopefully this clears everything up, but I can understand if there are any further questions. Let us know if you need any more help!