3CX allows allows you to import audio files files only in this below WAV format to use be used as the system prompts:
- Format: WAV
- Channel: Mono
- Bit rate: 8 kHz
- Sampling: 16 bit
To convert an audio file (for example an *.mp3 file ) to the appropriate format with the 3CX your professional recording company has created for you) you can use its this Online Audio Converter Tool at below link: