pocket message 

Either an answered call, voice mail message, or text message that has been made from a person's pocket. You might here an interesting conversation, your friend singing horribly to a song in their car, or just the sound of their pocket. Without a lock on your phone's keyboard, this might happen often.

You get a call from someone you haven't spoken to in years only to find out that they still don't want to talk to you because their phone dialed your number on accident, and as a result, you get a "pocket message", hearing the ruffle of their walk, or a conversation they are having with someone else.

pocket message by SeattleGirl10 March 1, 2010

Pocket Message 

A call made via cell phone that was unintentional in which made it to another’s voice mail; usually as a result of being unlocked and placed in a pocket or purse.

Joey left 3 pocket messages for me last night. Sounded like he was at some happnin party!

Pocket Message by DJ Jack Master Flash August 7, 2008