I almost always take my CP with me when I ride. Especially on my commute. If I get a flat, I need to call work and let them know I'll be late.
Other than that, if I get a call while riding, I always let it go to voicemail. I'll pull over and check it, just to make sure it's not my wife calling to tell me one of our kids has to go to the hospital. I never let it ring though. I have it set on silent, and a beep lets me know I have a new voicemail. :thumbup: