Well, I don't own a cell phone (gasp!). In the summer, I take night walks every night, usually with Tasha, sometimes with both Tommy and Tasha. I've always done this, when I was younger I took midsummer night walks with my collies too . They are some of the most peaceful times for me.

I think in this hypothesis, a dog definitely serves as a deterrent for anyone up to no good, however if you were just walking with a cell phone, unless it was in your hand with your finger on the auto-dial, I don't see how you could for sure get a call off if someone were to grab you.