Technically, this is illegal in the US but many business do it. Years ago it was common to contact the radio station and get a letter stating you had permission to do it, but my understanding is that doesn't work anymore.
But why would you want to? Most of modern broadcast radio is 10-20 minutes per hour of advertising, so you could potentially be playing your competition's commercials to your customers while on hold... Just as one example.
You are best off to use a licensed MOH source, a custom made MOH source tailored to your business, or simple instrumental music