How do i block a number that is not in my list

If you need to block outgoing calls, only your carrier can do this. If you need calls that you receive to be blocked, you must know the numbers you want to block, and possibly create a contact with all the numbers encoded, and then block.

Which numbers you have called and how you will be charged for it is solely a matter between you, the number you have called and your carrier. The only thing you can do yourself from your iPhone is to block incoming calls. Everything else is a carrier matter.

In order to block a number, it requires that the number is part of your contact list, or that the number can be found in the list of recent calls or missed calls. If you want to block a number directly from the recent call list, tap ( i ) next to the number, scroll to the bottom and select "Block this Caller"

If you have the number in Contacts, you block it here:

Settings → Phone → Blocked Contacts → Add New...

You can find more useful information here:

Block phone numbers, contacts, and emails on your iPhone or iPad - Apple Support

It seems that the free number is not completely free after all. But yeah, that's hard to answer precisely, since it's more of a carrier thing, and not so much an "iPhone specific" thing. But you are welcome, and I agree that the solution could perhaps be another carrier.