Trademarks indicate the source of goods or services. They are most frequently brand names, logos, and slogans. Trademarks can be used in many ways (see my post: 50 Ways to Use Your Trademarks). I recently came across another way — in your businesses telephone recording playing to callers on hold. What a great way to communicate to your customers and potential customers about your brand. Instead of hold music, a message about an upcoming promotion, or something interesting about your business’ story, could be interesting.
The USPTO has recognized that using a slogan in a hold recording is evidence of using a trademark in commerce. I know because I recently submitted such a recording in connection with an application to register our clients’ mark. (All of this is public record, of course.)
Audio specimens are accepted by the USPTO. For example, a radio commercial could also demonstrate use of a trademark.
You can hear the “hold” recording submitted to the USPTO that demonstrates use of the WHERE THE POWER IS trademark here:
http://tsdr.uspto.gov/documentviewer?caseId=sn85905523&docId=SPE20130919141257#docIndex=8&page=1