Hi Marco Federighi,
I trust you have read and applied to pay voluntary NICs while abroad from the following link
Social Security abroad: NI38
Once your CF83 application has been accepted to pay voluntary NICs from abroad the correct bank details are:
Account Name: NIC Receipts
Account Number 30944397
Sort code : 20 20 48
Reference: your NI number followed by IC then surname and initials up to 18 digits.
The other bank details is a valid account, it is used for UK Voluntary Class 3 payments.