List the phone number of the customer who placed orders with a total price of more than $300,000.
phone number refers to c_phone; a total price of more than $300,000 refers to o_totalprice > 300000
SELECT T2.c_phone FROM orders AS T1 INNER JOIN customer AS T2 ON T1.o_custkey = T2.c_custkey WHERE T1.o_totalprice > 300000