I was reading this news article and I knew that it sounded familiar to an old post. Desperado mentioned this scenario before, so I figured that I would tack on to his original thread.

One severed fiber optic line just south of the San Francisco Bay Area cuts off all phone service--landline and cell--to parts of three counties. Granted, it's not a densely populated region, but the total number affected is also not that small. The phone companies are telling people that if they need medical attention, be prepared to drive yourself to the hospital because you may not be able to dial 911 at all. Yikes, that sounds rather frightening when it's the phone companies telling you this.

Here's the article.