请等半个小时后打电话

都不一定是当事人接的电话 所以不一定是me拉

Please call back half an hour later 就可以拉

Please call me half an hour later. (一定要有 an)

Could you please make a phone call in about half an hour?

Please phone me half an hour later.

Please call back in half hour.

call me after half an hour