eBay auction snip:
This model has the following features and capabilities:
* State of The Art Security – Almost Impossible To "Listen Into Encrypted Conversations"
* Optional On Hold System Can Be Utilized By Simply Hanging The Unit On A Nail In The Wall (Nail Not Included).
* Waiting On Hold Music Is Available By Placing Unit Near Radio or Other Audio Source (Radio Not Included).
* Beveled Edges To Prevent Harmful Cuts While Speaking Or Listening.
* Caller ID Could Be Possible, If Holes Were Drilled Into Each Side Of the Unit.
Link to BubbaTel (TM) auction. (Thanks, Oxblood Ruffin!)