Life in prison has got to be one of the worst ways to deal with a criminal. If you think that the danger posed by DUI is worth life in prison, then it should apply to texting/phone use too.
It is people who knowingly put themselves in a situation where they kill people. It isn't about dealing with them, it's about protecting the rest of us from them. Typical prison may in fact be wrong -- an isolated island without vehicles where they can work and participate in society remotely would be okay for the ones who haven't murdered anyone yet.
I don't know about the jail punishment, but I see no reason that DUI punishment shouldn't be equal to phone/text punishment (and it should certainly be a license suspension of massive length).