The relatively small mouthpiece of this unmarked conversation tube may also have been used as a stethoscope.
Whilst there are usually fairly clear distinctions between the two this particular model may have been marketed as both See this article. The mouthpiece is unusual being of a convoluted rather than a simple horn type and is finished with a bronze lacquer. The tube itself is made from a coil of metal which retains flexibility. The date referred in the above article is 1850 which is I believe may be a little early but this was certainly a 19th century device.