Verb conjugation of "callar" in Spanish

I ordered a cab at four o'clock in the morning which took me to the Central Bus Station. I was much to early because the bus would go just at seven o'clock. Anyway I was sitting there and listening to music.
It is an abandoned place in the middle of Spain, in the middle of nowhere. The station is located near a junction where the ways of the trains split. Both are split as well, in their minds.
Your offer seems interesting to me. The language exchange is one of my future projects, so that we will contact you later when I am ready to discuss the ways and possibilities of learning together.