When there's an incoming phone call, a Sena should say something like:
"Incoming call, answer or ignore"

We could then simply say "answer" to recieve the call, or "ignore" to end the call.

Currently shouting like a banshee into the mike to answer the call is a bit embarrassing, and I'd rather not have to take my hand off the handlebars to answer a call. 

The Plantronics Voyager has a very good example of this functionality.