Set mp3 file as microphone input during call

I need a technical sollution to use mp3 file as input for phone microphone during call. Any audio adapters, Android software, iOS software or phone mirroring app for Windows, Linux or MacOS that makes calls using computer audio file output would work. Because my phone operator doesn’t give a possibility of uploading a voicemail message, but only recording it directly to the microphone and I have a mp3 file ready whose quality I want to preserve, this would be the only way to solve my issue.