How did God communicate with His people between Noah and Abraham?

I do not see the difficulty with Terah, because Terah fathered three sons, one of whom was Abraham, and it was Abraham God spoke to when he was seventy-five, in Genesis 12; that is where the break from Terah's idolatry comes. As for the people between Noah and Abraham, it is largely left blank for us. We know Noah called on God, because the whole world was saved through him, so he must have been a great man, and we assume Shem followed in Noah's footsteps, but we know nothing about Shem, nor about the remaining patriarchs in that genealogy, Arphaxad, Shelah, and the rest. The only reason they are named is that they served as reference patriarchs for the calendar, just as I say this is 2026 in the year of our Lord; they would say this is such-and-such a year in the year of Arphaxad, and when he died they would take someone born in that year as the next reference patriarch. Genesis 4:26 says men began to call on the name of the Lord, so there was a line that called on the Lord and a line that did not, and most did not, just as today, until the flood came and punished them all.