function validateNotEmpty( str ){
   if( str.length < 1 )
       return false;
   return true;
}

function validateNumericAndLength( str, len){
    //length = 0 is OK
    if( str.length == 0 )
        return true;

    if( str.length < len )
        return false;

    var i = str - 0;
    if( isNaN( i ) || (i < 0) )
        return false;

    return true;
}

function handleTextMessageDisplay(){
    var pForm = document.accountForm;

    if( !validateNotEmpty( pForm.areacode.value ) ){
        return;
    }
    if( !validateNotEmpty( pForm.phoneprefix.value ) ){
        return;
    }
    if( !validateNotEmpty( pForm.phonepostfix.value ) ){
        return;
    }

    if( !validateNumericAndLength( pForm.areacode.value, 3) ){
        return false;
    }
    if( !validateNumericAndLength( pForm.phoneprefix.value, 3) ){
        return false;
    }
    if( !validateNumericAndLength( pForm.phonepostfix.value, 4) ){
        return false;
    }

    //enable text messaging notification
    pForm.textnotify[0].disabled = false;
    pForm.textnotify[1].disabled = false;
}