SQL SERVER - UDF - Validate Integer Function

I received quite a good feedback about my post about SQL SERVER - Validate Field For DATE datatype using function ISDATE() One of the most interesting comment I received from my reader from Canada. I was suggested just like ISDATE() to write about ISNUMERIC() which can be used to validate numeric values. As per BOL: ISNUMERIC returns 1 when the input expression evaluates to a valid numeric data type; otherwise it returns 0. ISNUMERIC returns 1 for some characters that are not numbers, such as plus (+), minus (-), and valid currency symbols such as the dollar sign ($). Now this is issue with ISNUMERIC() function. It even suggest variable as numeric when it is not. I use following function to validate instead of ISNUMERIC() to validate if number is numeric or not.