Blowing shofar for Rosh HaShanah and for Yovel

My friend told me during the holiday that when the temple stood the shofar was blown for two reasons - to announce Rosh haShanah and for Yovel.

The Yovel is a year after counting seven cycles of seven shmitah cycles. It symbolized freedom, it is the time when all property is returned to its original owners, when slaves are freed.
On the other hand Rosh haShanah is the day (or two) when we coronate G-d, when we declare that haShem is our King - Melech Malkei haMelakim.

What is the relation between these two uses of shofar?

And the answer is that only one that is free can decide to have a king.

This thought gives us a hint on how to daven (pray) on Rosh haShanah - we have to start with knowing that we are free men with free will and as such we want haShem to be our King and to serve him.