5. Don't click on the "phone [recent]" number in the info panel; that will make a phone call. Don't right-click it either; that will do nothing.
4. Click "Create New Contact".
6. Select the phone number and copy it.
7. Click the "X" in the top left to avoid actually creating a contact.
8. Click "Discard Changes" even though you have made no changes.
It is actually easier to just take a screenshot at the first step, paste it into Preview, and copy the OCR'd number out.