Originally Posted by Yo Spiff

I keep my phone in the upper storage compartment of my Camelbak, where it is inches from my ear and I will always hear it. I usually won't stop to answer it, but I'll check it and return the call when i take a break. If my wife needs me immediately, our understanding is that she should immediately call a second time to alert me that I need to stop and return the call.

I have a small top tube pannier that my wife puts her phone and quick access items into on the tandem. It's a good option for those bikes that have brake cables running along the top tube that can't have tight straps against them. It's not sealed against weather however.