The most engaging messages are slightly unique in nature. They combine a mix of clever scripting and music. Slight humour is often used to promote a product or service and is usually quite effective. It's also very important to choose both the written and spoken tone that appeals to the characteristics of your audience. If your target market is the younger generation, a script that includes slang words and is quite laid back would be an excellent choice. If your target market is primarily business professionals, then a more articulate choice of words would be more suitable.
Below are some of the the companies who have trusted Advanced Productions with their on hold messages and IVR greetings.

Solo guitar and piano music can also be decent choices provided you avoid songs with extremes of high and low volumes and pitch. Most phone systems come with default tracks that, coincidentally, fall squarely into these categories. If you’d like something a bit different then you can find plenty royalty-free tunes available to purchase online (they’re not all that terrible), but remember you'll need to pay for a PRS license if you want to make use of tracks by a recording artist.
Hold music keeps your callers distracted from the wait, although it should not be considered a fix for long queue times.