I Solved this by using the below code
if ($("#ctl00_ContentPlaceHolder1_txtaddPhone2").val() == '') { $('#divphone2').hide(); }
if ($("#ctl00_ContentPlaceHolder1_txtaddPhone3").val() == '') { $('#divphone3').hide(); }
if ($("#ctl00_ContentPlaceHolder1_txtaddPhone4").val() == '') { $('#divphone4').hide(); }
Thank you very much to one and all for your help.
-Nag