Plausibility: Harmonic telegraph instead of the telephone

Research into the harmonic telegraph, a telegraph that could transmit multiple messages down the same pair of wires, led to the invention of the telephone IOTL. Is it possible that the harmonic telegraph could have been widely adopted, delaying the invention of the telephone significantly? What would be the effects of this?
 
These are not competing technologies. The harmonic telegraph was designed for high-volume signal traffic (and the basic principle is one we are using to post here, so you could argue a superior version was adopted). The telephone is designed to transmit a broader signal, and the property of carrying voice made it useful to people who had no use for telegraphs. Different markets, different purposes.
 
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