This means OnSIP customers can now insert custom music, advertisements, company announcements, self-recorded messages, or any other pertinent audio media, into their on-hold music. Additionally, these custom messages can be scheduled to play at specific times on specific days!
It seems pretty self-explanatory: on-hold messages are messages that play “on hold” over your telephone system. These professionally produced recordings are also an integral part of your company’s marketing strategy. By providing timely, relevant information about your business, an on-hold messaging program reinforces current marketing campaigns and builds brand recognition. This in turn increases call retention by improving the caller experience. To top it all off, it also increases sales by targeting key demographics.

The way all your words and sentences come together gives your script a distinct written tone. Combine that with a specific speaking tone to create an on-hold message that reinforces your brand and product set. Selecting the correct tones will ensure your intended message is communicated effectively. If your target market is the younger generation, then a tone which embodies fun and excitement would be most suitable.
If it is a genre, hold music, it's fair to say, is a troubled one with few hits. It's not really meant to be loved or even listened to — it's meant to communicate something specific: Don't hang up. (Cornell makes this plea specifically at the end of his song.) Silence is believed to be a death knell for phone calls — people will simply think the line is dead and hang up. This is true even on non-hold calls; it's why phone companies transmit something called a "comfort tone" over phone lines, a barely audible synthetic noise that signals a connection is still there.