In spite of the optimism expressed by Valdemar Poulsen about the near-term prospects for magnetic recording, his telegraphone would need many decades of refinement before the development of a practical system of magnetic recording and playback.
Telephone Magazine, May, 1904, pages 183-184:

By  Dr.  Alfred  Gradenwitz.

The  Use  of  the  Telegraphone  in  Telephony.
    V. Poulsen's telegraphone in its original form records sound waves on a steel wire or ribbon wound on a cylinder. The telephone currents produced by a microphone are conveyed to an electromagnet in front of the poles of which the above wire or ribbon is moved along when the relatively weak currents will excite magnetism in its different parts as it passes by. As this magnetism is permanent, it may serve to fix language. When the words recorded are to be reproduced, it suffices to run the steel wire in the same direction in front of a similar electromagnet to the windings of which a telephone is connected. As the different parts of the wire show differences in magnetism, there will in the windings of the electromagnet be produced corresponding induction currents, which in turn will act on the telephone.
    The inventor recently gave an account before the Copenhagen Industrial and Hygenic Congress of the improvements made in connection with this apparatus since the appearance of its first type, as well as of the hopes he attaches to the telegraphone. The fact that a somewhat intense respiration will easily be recorded and reproduced by the apparatus is illustrative of the sensitiveness of the latter. In the latest type of the apparatus, the wire is replaced by a round and thin steel disc, which may readily put into an envelope and sent anywhere in order to be reproduced by another apparatus, thus affording quite a novel means of correspondence.
    A special application of the telegraphone is the so-called telephone newspaper, being an apparatus capable of distributing the same language, music, etc., record to any desired number of auditors. An endless steel ribbon is laid around two rotating discs, drawing it along in front of an electromagnet recording the news transmitted. The iron ribbon next passes before a great number of so-called "reading-magnets" being arranged in a long series after one another and capable of being put in connection with the same number of telephone lines independently of each other; the record finally reaches an obliterating magnet and afterwards passes again in front of the recording magnet, and so on.
    On account of its principle, the telegraphone seems to be especially suitable in connection with telephones in big offices, for recording the conversations which take place in small offices at the same time for giving and receiving notice in the case of the subscriber being absent. In America, such communications have been recorded on an apparatus, located in a subscribers house in New York, Washington when the reproduction in spite of great distance over which record was made was exceedingly distinct.