function submitReservation(f) {

    var isOk = true
    f["btnSubmit"].value = 'please wait...';
    f["btnSubmit"].disabled = true;
    if (f["phone"].value=="" && f["email"].value=="") {
        alert("Please enter your phone number or email address.")
        f["phone"].focus();
        isOk = false;
    }

    if (!isOk) {
        f["btnSubmit"].value = 'Submit';
        f["btnSubmit"].disabled = false;
        return false;
    }

    if (isOk)
        f.submit();
    
}