From Israel comes this innovation that enables cell phone users to conduct conversations while being quiet.  Silent Communications, an Israeli startup, has a technology that allows users to carry a two way conversation without making sounds and bothering others in settings such as a meeting room, a concert or a lecture hall.

The secret is using pre-recorded voice messages.  The end-user is able to hear the other caller and can respond by selecting one of these pre-recorded responses.  These messages can be customized, and use either the standard ones that come with the product or personalized ones that are recorded by the user on his/her own. 

I'd be willing to bet that Max Bluvband (the inventor of this system, called TWT - Talk Without Talking) must have somehow gotten the idea from the voice messaging industry, where pre-recorded messages are taped by vendors such as Nortel and come with the standard voice mail / unified messaging packages (e.g. Meridian Mail or Call Pilot).  But what's unique here is the ability of the end-user to create his own unique set of personalized canned messages that could be chosen on the fly, depending on what the person on the other end is asking.