How do I put do mp3 playback in a vintage phone please? Answered

Wondering if this is possible. I would like to make an old landline vintage style phone work so when I pick up the the earpiece, it automaticaly plays an mp3 through the earpiece .until its set down again.

The style of phone I have is the one where the talking piece hangs on the side. Can anyone give some advice on how to do this please or point me in the right direction.

Cheers