Although referred to in this article as a "telephone", Elisha Gray's device wasn't capable of full audio, and actually was a type of "harmonic-telegraph piano", which could only produce a limited number of simple tones. Still, the fact that it could be operated in Washington from Philadelphia over a telegraph line made it a marvel of the day.

The original scan for this article is at: https://chroniclingamerica.loc.gov/lccn/sn86053573/1877-04-10/ed-1/seq-1/
 

National Republican (Washington, D.C.), April 10, 1877, page 1:

MUSIC  BY  TELEGRAPH.
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THE  TELEPHONE  EXHIBITION  AT  LINCOLN  HALL.
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A
irs  Played  In  Philadelphia  Distinctly  Audible  In  Washington--Description  of  the  Apparatus--Its  Sound and  What  It  Resembles--The  Performance  a  Great  Success.

    The atmospheric conditions last evening were far from favorable to the reception of music by telegraph, and it was not surprising, therefore, that the majority of those who went to Lincoln hall last evening to presence the latest triumph of American science--the telephone--were more or less doubtful of the success of the experiment they were about to witness. The interest manifested by our citizens in this grand and important invention could not have been attested in a more substantial manner, for the hall was filled to almost its amplest capacity by as intelligent and discriminating an audience as has gathered in that resort this season.
    The preparation for the exhibition of the telephone were quite simple and were easily observable. Several wires depended from the aperture over the chandelier in the centre of the room, and communicated some with a regular telegraphic instrument on the stage to the left of the audience, others with the receiving apparatus of the telephone. The latter was placed on the floor of the stage, to the right of the audience. It is a small apparatus, about six feet long and less than two feet high, and consists of sixteen square boxes, resembling in appearance and arrangement the tubes of a large organ.
    The entertainment began with the concert which Mr. Maurice Strakosch had provided, evidently to offset any disappointment that the audience might experience in the event of the inability of the telephone to surmount the obstacles of the inclement weather. The following was the programme:
PART  I.
1. Concert Polonais,Rubenstein.
Mr. S. Leibling.
2. Brilliant Air from "Mignon,"Thomas.
Miss Fanny Kellogg.
3. "Romanza," from Ill Ballo in "Maschera,"Verdi.
Signor Tagliapietra.
4. Rigoletto Fantasia,Liest.
Mr. S. Leibling.
5. "Let Me Dream Again,"Sullivan.
Miss Fanny Kellogg.
6. "Les Rameaux,"Faure.
Signor Tagliapietra.
SECOND  PART.
    Performances on the Telephone in Philadelphia by
Mr. F. Boscovitz.
THIRD  PART.
1. Valse Brillante,Bendel.
2. "Mia Picoirilla," a beautiful song,Gomes.
Miss Fanny Kellogg.
3. "Non e Ver,"Tito Mattel.
Signor Tagliapietra.

    Miss Fannie Kellogg is a young lady of prepossessing appearance, but evidently still a novice in the concert-room. Her rendition of the Polonaise from "Mignon," which is an extremely difficult passage, requiring the greatest flexibility and control of voice, was not even a mediocre performance, although she took the liberty of omitting the trills and substituting a few notes of her own for those of the composer, and to cap the climax the finale of the air was sang entirely out of key as well as out of time. Indeed, it was as complete a faux pas as we have ever witnessed at a first-class concert. Miss Kellogg, nevertheless, found many admirers, for she was loudly encored, and in response to repeated calls essayed that sweet and plaintive air of Apt's--Embarrassment--which she sang but indifferently well. To Signor Tagliapietra we cannot award too much praise. He was in exquisite voice, and his singing was perfection itself.
    Mr. S. Liebling's performance on the piano was artistic and finished.
    At the conclusion or the first part of the concert the piano was closed, and two young men raised the "receiving" apparatus of the telephone and placed it on the piano, after which a wire was adjusted to it, thus establishing direct communication with the "sending" instrument, in the office of the Western Union Telegraph Company in Philadelphia, presided over by Mr. F. Boscovitz.
    A telegraph operator next appeared and took up his position at the little table above referred to. Immediately afterwards a tall, spare gentleman with a beard came forward. This was Professor Gray, the inventor of the telephone. The Professor declared that he did not desire to exhibit the telephone as a great musical instrument, and if anybody expected to listen to grand music, he would inform them in advance that they would be disappointed. The Professor, although doubtless a genius in some respects, cannot be said to number oratory among his gifts. In a rambling, disconnected and ungrammatical speech, out or which it was impossible for the life of us to make head or tail, the Professor endeavored to explain in a scientific manner many things connected with the telephone. He was not permitted to continue the infliction very long, for the audience grew impatient, and manifested their feelings in a quiet way.
    The Professor was not slow to take the hint, and concluded his introductory remarks by requesting the greatest silence. He then directed the telegraph operator to inform Mr. Boscovitz at Philadelphia that everything was in readiness and he might begin. Within three or four seconds the first notes of "Home, Sweet Home" were distinctly audible in every part of the spacious ball, the melody being recognized perfectly.
    We can best describe the music of the telephone as heard last night by comparing it to the sound that would be produced slowly on an organ with one finger. The higher notes were rather feeble. The utmost stillness prevailed, and at the finish the applause was long and enthusiastic. The remaining selections on the programme were played in the order given, all with the same success, as follows:
    1. "Home, Sweet Home."
    2. "Come Genil."--Don Pasquale.
    3. "Then You'll Remember Me"--(Bohemian Girl.)
    4. "The Last Rose of Summer."
    5. "M'Appari," Romance--(Martha.)
    6. "The Carnival of Venice."
    At the conclusion of the exhibition the judgment of all present was highly flattering to what may yet be numbered among the greatest inventions of modern times.