Get different sums from the same table in one query

Hi all!

I want to put this three queries in only one... Take a look that the
only thing that changes is the message_type_id. Any suggestions??

SELECT TO_CHAR( statistics_date, 'DD/MM/YYYY') AS date_in,
sum(total_num_messages)
FROM statistics_daily
WHERE message_type_id IN (4,5)
AND statistics_date = CURRENT_DATE
AND telecom_operator_id <> 0
AND telephone_number IN ( $numbers )
GROUP BY date_in

SELECT TO_CHAR( statistics_date, 'DD/MM/YYYY') AS date_in,
sum(total_num_messages)
FROM statistics_daily
WHERE message_type_id IN (6)
AND statistics_date = CURRENT_DATE
AND telecom_operator_id <> 0
AND telephone_number IN ( $numbers )
GROUP BY date_in

SELECT TO_CHAR( statistics_date, 'DD/MM/YYYY') AS date_in,
sum(total_num_messages)
FROM statistics_daily
WHERE message_type_id IN (21)
AND statistics_date = CURRENT_DATE
AND telecom_operator_id <> 0
AND telephone_number IN ( $numbers )
GROUP BY date_in

Thank you in advance!