A man and I have been in one another's lives for the past two years. We have a friendship but are attracted to one another although we both have other feelings. Recently he provided me with a cell phone to use where he erased all phone information with the exception of two voice memos he had left on the phone. When I played them both it was a one sided recording of a woman who said things like "I want you more now", "I trust you", etc. I have never heard the woman before and don't understand why the messages are there.

I know they were left there intentionally but I don't understand why or what he may be looking for... any advice?

Two choices. Confront him about it or STAY AWAY.

It sounds as if he wanted to see if he could spark a jealous reaction out of you.
Many people erroneously believe jealousy equals love.
Game playing and rather immature.