function validate_required(field,alerttxt)
	{
		with (field)
		{
		if (value==null||value=="") {alert(alerttxt);return false;}
		else {return true}
		}
	}
	
	function isNumeric(elem, helperMsg)
	{
		var numericExpression = /^[0-9]+$/;
		if(elem.value.match(numericExpression)){
			return true;
		}else{
			alert(helperMsg);
			return false;
		}
	}

	function isLentghOk(elem, min, max, helperMsg){
		if(elem.value.length >= min && elem.value.length <= max){
			return true;
		}else{
			alert(helperMsg);
			return false;
		}
	}

	function validate_form(thisform)
	{
		with (thisform)
		{
			if (validate_required(mobile,"You must enter your mobile number.")==false) {mobile.focus();return false;}
			else if (isNumeric(mobile, "You may enter numbers only!")==false) {mobile.focus();return false;}
			else if (isLentghOk(mobile, 10, 15,"You must enter a valid number!")==false) {mobile.focus(); return false;}
		}
	}