A voice memo is a audio message usually lef for oneself to remind you of something.Some cell phone has the ability to record voice memos.Ex. Select voice memo on phone and say "Doctors appointment at 3:30 on January 6th."
BPO means Business Process Outsourcing; I'm assuming you mean the same thing. I would imagine that "non-voice" BPO jobs would be ones that do not involve communicating by voice with the customers....