My cell phone and work number are two of the most closely kept secrets in our company. It's not that difficult to get to me IF you go through the proper channels. If you try and bypass the proper channels you will never talk to me again. Even internally you have to go thorough the proper channels.
At first our CEO didn't like this but then I asked him if we have a major outage what do you want for me to do? Chat it up with customers or fix the problem?
I worked at a place where everyone and anyone had all of your numbers. When something did break it was stressful and counter productive for your phone to ring every 30 seconds with some guy asking you the same damn questions the last guy asked.