Filtered Textbox extender text without hypen.

Hi guys 

            Hi have a simple doubt in filtertextboxextender, i used a filteredtexboxextender for textbox with "999-99-9999"(SSN no) format but im getting  textbox value as 123-45-6789.

Is there any option to avoid hyphen while getting value in codebehind. I want txtSSN.value="123456789" instead of "123-45-6789".I just want to display these hypehen while editing the text.