function validateCallUs(f){
	if (isBlank(f.fullname.value)) {
		alert("Please enter your name");
		f.fullname.focus();
		return false;
	}
	if (isBlank(f.telephone.value)) {
		alert("Please enter your telephone number");
		f.telephone.focus();
		return false;
	}
	if (!isNumber(f.telephone.value)) {
		alert("Please enter your telephone number using numbers only");
		f.telephone.focus();
		return false;
	}
	if (f.callback.selectedIndex==0) {
		alert("Please let us know when you would like to be called");
		f.callback.focus();
		return false;
	}
}

function isNumber(v) {
    	if (isNaN(v.replace(/ /g,""))) {
    		return false;
    	}
    	else return true;
}

function isBlank(v) {
	if ((v.length>0) && (v!=" ")) {
		return false;
	}
	else {
		return true;
	}
}