Regex expression for numbers having more than 4 digit

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C#

Hi friends,

I am using regex expressions in my project to extract the phone numbers..
Now, I am using an expression like this ..

var exp = new Regex(@"#?[0-9\s\-\(\)]{4,20}", RegexOptions.IgnoreCase);

What I want is to get the numbers having more than 4 digits.
But its counting everything in the expression... For eg: It returns (20) and this too....
How can I choose only if the numbers are more than 4 digits, and select the rest if it contains this special characters...

Sorry for my english...