[kbutler]

It works quite well - though I disagree with his reluctance to hold it up to the mouth like a mic (speaking only) rather than up to your cheek like a phone (speaking and listening). It's usually More comfortable to me. Maybe we are just doing it in different contexts.

Either way, making it immediately obvious you're talking into a device gives the implicit signal "I'm talking, but not to you" so you don't have to do any further signaling, which is usually less clear anyway (head shake, etc.)