MySQL query:

SELECT *
FROM   (SELECT name,
               `phone_number`,
               IFNULL(SUM(cr1.duration), 0) + IFNULL(SUM(CASE WHEN cr2.duration
               < 120
                      THEN 500
               ELSE 500 + (cr2.duration - 120) * 2 end), 0) AS call_units
        FROM   `customer_detail` cd
               LEFT JOIN `call_record` cr1
                      ON cr1.`incoming_number` = cd.`phone_number`
                         AND cr1.dialed_on BETWEEN '2018-09-01' AND '2018-09-30'
               LEFT JOIN `call_record` cr2
                      ON cr2.`outgoing_number` = cd.`phone_number`
                         AND cr2.dialed_on BETWEEN '2018-09-01' AND '2018-09-30'
        GROUP  BY phone_number) `Bill`
WHERE  bill.call_units > 0;