Hi @daniyal.arshad,

welcome to the o2 community!
You can use this form in order to reclaim the remaining sum from your prepaid account and to ask for your number to be released for transfer.
Just fill in the details like your SIM card number, phone number, and bank details.

In order to also take your phone number to your o2 postpaid account, make sure to check the box next to “Ich möchte die Prepaid-Rufnummer zu einem anderen Anbieter portieren.” on that form.

Please keep in mind that by sending the form in, your prepaid account along with your phone number will be terminated permanently!

After it has been confirmed that your prepaid account will be ended, you can order your phone number to be imported to your o2 postpaid account:
The easiest way is via the Mein o2 App or the Mein o2 account of your new postpaid account, just choose "SIM verwalten" and look for "Rufnummernmitnahme / Zu o2". In order to make the transfer work, please make sure that your personal data is exactly matching in both your o2 accounts.

Then, your prepaid phone number should be imported and implemented to your postpaid account within a few days.

Best regards,
Jan.