Find Free Number Ranges of Customer and Vendor Accounts

Hi,

We have a requirement where we want to report to customer the free numbers present in customer and Vendor Accounts Groups.

To solve this, I went through XKN1 and XDN1, where I go the current number for each Vendor and Customer Account Group.

But the customer is having a strange requirement. They want to know, the free numbers available in these customer range.

Please see the attached doc for the requirement and the solution which has been given.

Please let me know, how to find the free numbers available in SAP system.

Regards,

Devdatth