You can try using Pivot to make the two phone numbers to one and then use CountD on that.
PFB Steps and use the attached sheet too.
Right click the two columns - Phone, Phone Mobile
Hide the Pivot Field Names & Rename the Pivot Field Values to Phone Number.
Make the phone number to String.
Now Try COuntD
Phone Number Combine.twbx 4.9 KB
Another approach could be use coalesce or nvl function in custom sql. coalesce(phone,mobile) in first query and in second query coalesce(mobile,phone) then union this 2 query. You would get the desired result.
(Example I used is of Oracle database, feel free to reply for further clarification)