Most companies used to have repeat messages or nothing at all while callers were on hold, but the trend is now towards radio and advertising on hold through messages and customized music. Radio on-hold is advantageous in that the company does not have to spend money on professional voice talents,
American Creative Blog
There is a trend towards On hold marketing messages for callers waiting on hold and away from on hold radio or dead silence while holding. Advertising on hold is gaining popularity because most callers will drop the call when they are put on hold if there is no engaging information being communicated.
On hold music, as the term suggests, is the music that is played while callers are on hold. The music could be mainstream music or music produced for the company for phone advertising. This music is important because between 16% and 20% of callers make a purchase depending on the