Teshuvah and Shofar

The Rambam (Teshuvah 3:4) writes, "Although blowing the shofar on Rosh Hashanah is a gezeiras hakasuv (a Torah decree), the shofar is telling us something. The shofar is shouting, משנתכם ישנים עורו— Those who are sleeping, wake up from your sleep! Examine your deeds and repent. Remember your Creator, all those who have forgotten the truth."