In "The Telephone Gambit: Chasing Alexander Graham Bell's Secret," journalist Seth Shulman argues that Bell — aided by aggressive lawyers and a corrupt patent examiner — got an improper peek at patent documents Elisha Gray had filed, and that Bell was erroneously credited with filing first.
I found this line most intriguing:
Bell, not Gray, actually demonstrated a phone that transmitted speech. Gray was focused instead on his era's pressing communications challenge: how to send multiple messages simultaneously over the same telegraph wire. As Gray huffed to his attorney, "I should like to see Bell do that with his apparatus."