My ole' man spent 25 years in the telecom industry. He started with MCI, but then became an employee of the notorious WorldCom (I'm sure many of you know that story). During the consolidation and change in technology in that industry, he saw revenues corroded by deregulation and then further by VOIP services. In their attempt to adapt, MCI-WorldCom invested greatly into the VOIP technology. The only issue seen by those in the telecom industry was concern of "uptime." That is, telephony had achieved "five nines" of reliability--99.999% uptime (for those of you interested, this means that yearly downtime totals a whopping 5:16--not bad for reliability). However, VOIP phones because they are IP based did not initially have the coveted uptime of a regular phone line. As you can imagine, this posed some possibilities for major issues. While price made for a sizzling offer, unreliable service can certainly lead to a "value-subtracted" proposition. 
"Five Nines" in the digital signage arena means 5:16 minutes of outages in 365 days. That five minutes and sixteen seconds of down time includes downtime for security, downtime for networking, downtime for software, and downtime for hardware. Woah! That's a much more complicated impossity than a POTS telephone line. It makes one wonder whether "five nines" is truly possible in this sector.
Issues Plaguing Digital Media Networks without Five Nines
Before we delve into the various issues of the non-six sigma and the BSOD, let's talk about reasons we want our networks to be reliable.
1. Networks need to be reliable for reputation sake. Adcentricity gently reminded us that delivery problems hurt us all. The same goes for playback issues as well. Nothing good comes out of a partly functioning system of any kind, especially when it comes to reputation.
2. Security requires networks to be reliable. Not only can hackers insert their own content on an insecure sign network, but they can also reek havock on the uptime. I guess inappropriate content would be worse than the BSOD, but what does it reflect on your network security?
3. Signage networks must be the crutch in times of emergency. What good is an emergency alert function in your digital signage software if when the needed time arises, your screens are not working? What a waste of a good investment.
4. Money is always an issue. If you think it is not, you're crazy. When networks default, it costs money. Not always is digital signage about advertising. Outages cost money in other ways. For instance, time and resources to get the network running again requires personnel and personnel require money. Reliability is akin to sustainability and revenue.
What can go wrong with hardware
Think of where something could go wrong, and Murphy's law will most definitely take hold. The two areas of hardware that could most easily jack with your reliability include the LCD display itself and the media player. Sometimes the reliability of such devices could be a case of "you get what you pay for." Of course, I still own a working version of the cheapest MP3 player on the market from five years ago. I shopped based on price and got lucky. This may not be the case when seeking out an LCD display. There have reportedly been many problems with purchasing off-brand displays.
Another area that could interfere with the display's reliability is a faulty or busted RS232 control piece. If this goes "belly-up" on you, you could have issues with a fully functioning screen whose remote control device is defunct. While not the most optimal scenario, it is more easily remedied than other hardware failures that could occur.
What can go awry with software
There are two aspects of the software worth noting. First, the operating system your sign software is running on can make or break you, especially if you want to avoid the BSOD. I will not mention any names specifically. Versions of Linus and other open source software packages are becoming more popular not only for reliability, but also for cost. I recently read a news article about how the Paris police force replaced all their old servers with a Linux based solution. In so doing, it was predicted they would save literally millions of dollars in software and regular maintenance costs. The same holds true for digital media networks. There are a number of Linux or open source sign systems out there, including some cross-platform systems. However, this may not mean the software residing on the OS is five-nineable.
The sign software can be another issue entirely. It may not give you a blue screen of death, but it certainly can cause greater than needed headaches if chosen improperly. A reliable and tested software solution can make or break any signage network. I don't think I need to beat the horse deader-er.
Connectivity
Satellite, cellular, LAN, WAN, 802.11...what is your flavor? How are your screens connected? How often is the player heartbeat to the server? Is it a push or pull system? Does your player playback locally? Does your software require streaming? How often do the media feeds pull from an external source? Such rhetoric makes me less faithful in the ability of signage networks to achieve five nines. It seems as if there are too many ways to get it wrong.
Even in the most optimal of conditions, connectivity can go south with the birds. And for necessary emergency alerts, updated in a timely matter, this can pose a real issue and liability. Talk to any connectivity whiz and you'll know they would prefer you "hard-wire" connect over some other sub-par solution. Whatever your connection of choice, remember failure can happen here as well.
In conclusion, I want to reference something I learned in a developmental biology class some time ago. As we were learning about the development of a human being, we discussed the various things that could go wrong in development of the fetus; things relating to chemical deficiencies to physical maladies within the womb. Problems, resulting in abnormalities and death, can and do surface at nearly every juncture of human fetal development. In reference to this, I can remember the professor of the class commenting with something like, "believe me, it is amazing and miraculous that any of you turned out normal." There were chuckles in the audience, but he went on, "I'm serious. Count yourself blessed that you're not a chromosome shy and sitting in an institution somewhere drooling on yourself." While that was putting rather bluntly, he made his point. Similarly, it is amazing that digital signage networks ever succeed as well. With the litany of possible issues, sometimes you have to sit back and count your lucky stars. But, that doesn't give you an excuse to find some "run-of-the-mill crapperware" solution.
