Company web site:
http://www.vocera.com

This "wearable badge" works like a Starship Enterprise communicator and doesn't have a keypad. There is only 1 main button and 2-3 little helper buttons for volume control etc. Commands are issued using voice recognition, and its the Vocera server that does the recognition processing, not the badge itself (which weighs just 2 ounces).

Supposedly some "limited SIP" support is announced for future product revisions.