Before inventing the telephone, Alexander Graham Bell tried to teach his Skye Terrier to talk.
Bell's father was an elocutionist, and developed a system of symbolic notations to help people learn how to speak better. The notations were based on the shape and movement of the lips and tongue, and young Bell got quite good at writing and reading the notations.
When Bell's mother began to lose her hearing, young Bell, now age 20, got the idea that speech could be learned by simply manipulating the shape of the mouth, and that by careful training anyone could be taught to talk.
Short on practice dummies, young Bell turned to Trouve, the family Skye terrier, to prove the point.
Job One, as Bell saw it, was to get Trouve to stop barking and instead to vocalize with sustained growls, which he taught with food rewards.
Once the dog was sitting quietly and growling on command, Bell shaped the dog’s mouth to produce the sounds “ma, ma, ma.” After a long time and a lot of treats, the dog caught on and was saying the words in fairly human-like way. With a lot more work young Bell taught the dog to string along a few more sounds, and eventually the dog was using a string of sounds that sounded a bit like someone saying "How are you, Grandmama?”
That was about as far as things went, of course.
Dogs do not have human vocal chords or fleshy lips, so there is a limited range of sounds they can make. Nonetheless, young Bell's work was impressive enough that he found backers to stake him for for his other inventive pursuits, such as the telephone.