The following instructions will demonstrate how to create, add or remove audio files from an on-hold playlist.
Sign in to the 3CX management console using the administrator credentials. From the left menue select 'Settings', and then click on "Music On Hold"
From here you can Add, Record, and Manage your audio files, greetings, and recordings. If you want to upload an audio file from your computer, make sure it's in compatible WAV format using this guide.