Tolkien said that Sauron had the Ring in Númenor. And Tolkien said that Sauron had the Ring in Mordor, after the Drowning of Númenor.
How the Ring went from Númenor to Mordor is not known (at least I don't remember having read about it). Maybe the spirit of Sauron was able to carry the Ring or maybe he carried the Ring to Númenor before the fall ...