The old way of transferring a signal by low vision infrared light beams is long gone.  Now manufacturers have upgraded to the Bluetooth technology that mixes a blend of wireless signals to help find a frequency.  With older methods if there was something blocking the beam between the sending device and the receiver, the beam would be interrupted and the information wouldn't be passed over it any longer.  With bluetooth though, you can have walls and other obstacles in between yourself and the communicating device and this means that whether you are in your home or your office, that you aren't going to have to worry about dropped calls and poor reception.

For the most part, people use these devices with the cell phones so that they aren't reaching around when it rings, or fumbling through everything in their pocket to find the phone.  If they have a bluetooth headset they can easily press a button located next to their ear to either send the call to the voice mail, or choose to take the call and begin the conversation.  This hands free movement means that you can get a lot more accomplished throughout the day by not having to have your neck bent sideways holding the phone as you are stirring together a pasta sauce for dinner.  There are going to be other times where you know that there are important calls coming in, and are going to have your hands completely tied up unable to get to the phone.  Some of the more advanced, higher end devices will allow you to speak into them stating what you want to do with the call.  This is a life saver if you are a true go getter and find yourself in the position of missing calls because you are too busy.