sql qurey for duplicate customers : I want number of customers (count) and duplicate phone_no from a table. I have to remove dashes in phone number and then check the length is equal to 10. Please can any one help in sql query.

My query is like below,

select COUNT(Cust_ID) cnt,Phone_no from tbl_Customers where Cust_Type = 3
group by Phone_no
having COUNT(Cust_ID) > 1 
order by cnt desc