The ansible—a communication device which allows instantaneous, faster-than-light communication across interstellar distances—isn't Orson Scott Card's. He stole it, as sneaky authors will do, and it was originally invented by Ursula K. Le Guin in her 1966 novel Rocannon's World. LeGuin used it in the Hainish Cycle, a group of loosely related novels set in the same universe as Rocannon's World. The Hainish Cycle included two of Le Guin's best known books, The Left Hand of Darkness and The Dispossessed.
The ansible can be seen, then, not just as a communication device between worlds, but as a communication device between books. It's a signal that Card is talking to Le Guin, across the space between bookshelves. (Hey, Orson? Yes, Ursula? Give me back my ansible.)
The conversation between Orson and Ursula goes in a number of ways. On the one hand, Card is expanding on Le Guin's themes. Le Guin is known for approaching science fiction from an anthropological—rather than a hard-science and physics—perspective, and her books often focus on cultural differences and cross-cultural contact. For example, The Word for World Is Forest from 1976 (part of the Hainish cycle) focuses on the effect of human imperialism and greed on a tree-dwelling alien race—an obvious parallel to the plot of Speaker for the Dead.
Le Guin was also interested in exploring different sexualities and modes of reproduction, and The Left Hand of Darkness (1969) is set on a world where all the people are hermaphrodites, meaning each person is both male and female. Much of the novel involves thinking through what this means for culture, sex, and life.
So part of the discussion between Ursula and Orson is sympathetic chatter. Part of it, though, is more like argument, or negotiation. In Left Hand of Darkness, the alien hermaphrodites are altered humans, and a male human has a kind of almost love affair with one. Card is much more circumspect about this kind of romance with the other. The Hive Queen is in Ender's head and under his bed, but not in it, and Jane is a love but not a lover; the question of human/piggie sexual relations isn't even on the radar. Ender says "We'll change ourselves only enough that they can bear to live with us" (17.185).
Whereas Le Guin often seemed like she was eager and willing to try to change humans as much as possible—to throw out every preconception about gender and identity and humanness and see where it took her, Card's Catholic Brazillian colony named resolutely after Brazil seems to cling determinedly to tradition.
Borrowing the ansible could be seen as traditional too; it's a part of sci-fi past that Card is retooling as his own. For Le Guin it was a way to connect to new space, to erase distance in a mystical communication with the future. For Card, on the other hand, the ansible goes both ways—onward and backward. He's listening to the future with the ear of the past.