I'm looking at a database of mobile numbers and am trying to find errors.
For example, mobile numbers begin with '04', so to test for errors, I can query:
SELECT DISTINCT Names.Phone_M FROM Names
WHERE Names.Phone_M NOT LIKE '04%'
You can try ISNUMERIC () function
where ISNUMERIC (Names.Phone_M) = 1 -- should match valid numbers
where ISNUMERIC (Names.Phone_M) = 0 -- should match invalid numbers