In Katrina the power went out, the cell phone towers went down, the police multiplexing radio stopped working. The only communication people had when the water started coming into their homes were their analog phone lines. When everything else stopped working those remained operational. I still remember people calling in to a local radio station (from their landlines) to say that they were trapped in their attic and request help. Getting rid of analog phones is the worst idea I've ever heard and shows that that the people suggesting it have never seen the information black hole that results from a major disaster.