In 1878, Alexander Graham Bell set up the first telephone exchange in New Haven, Connecticut. Plain Old Telephone Service (POTS) has been around for over 125 years.

They've had all that time to make the service as reliable and usable as possible, given the technology they have to work with. Computer switching has replaced the old mechanical switches which had replaced live operators (around the 1950s). Wires are being buried underground for safety from storms (falling trees and such). Power for your home phone is provided by the system, no local power required unless you use a cordless phone. Some service is even provided over radio links to remote areas to save the cost and exposure to storm damage of hanging wire.

As a result, during natural disasters, the telephone system usually fails long after the lights go out, if it fails at all.

So, how can we make our VoIP system perform as reliably as the old telephone system?

In the following discussion, we'll assume that you've read the previous NaSPA article on Hosted VoIP Service or you have the service in house and are familiar with its inner workings.

The Risks

Your VoIP Service is made up of several piecesYour VoIP service is made up of several pieces (refer to figure 1). If the power goes out, the DSL/cable/wireless modem, your router(s), any switches or hubs (not pictured) and your VoIP phones and adaptors will no longer function.

If your Internet service provider (ISP) has problems, your phones will no longer work.

If the Internet itself fails (unlikely), you're out of luck (and so is everyone else).

And if your VoIP service interface to the POTS system or their Network Operations Center (NOC) goes down, you'll be inventing new words that would make a sailor blush (please calm down before contacting their help desk, you'll get a lot more cooperation that way).

Of all these problems, the most likely one is the power outage concern.

Prevention

VoIP Service with Uninterruptable Power Supply

The most obvious preventive measure is to protect the power supply to your in-house equipment. The easiest way is with an Uninterruptible Power Supply (UPS).

You probably already protect your computers with some form of UPS. It can be fairly easy to do the same for your VoIP dependent gear (see Figure 2). This will also give you the advantage of protecting your Internet connection and your internal network as well.

If you acquire VoIP equipment that runs on Power Over Ethernet (POE), you only have to inject power into your system at one point, assuming that your routers, switches, and hubs are designed to pass that power on. The added advantage is that the VoIP gear won't take up another wall socket and you only need to purchase one UPS that's large enough to run all the equipment hooked into it for as long as you think is necessary (and your budget can stand). Don't underestimate your power requirements when you purchase a UPS; your "one hour" solution might poop out after 15 minutes, especially if you try to power a thermal device such as a laser printer.

Just about any UPS manufacturer offers various capacities of UPS in both floor and rack-mounted models. Leading brands are Tripp Light, American Power Conversion (APC), and PowerWare. There are others. Pay attention to the shape of the wave the UPS you're considering puts out. More expensive versions often put out a pure sine wave, while others might only put out a square or modified square wave. Sine wave power gets along better with monitors and televisions as well as some other equipment. Check the equipment you're protecting to make sure they can deal with square wave power (a lot of stuff is just fine with it) before you settle for that cheaper unit.

If continued operation during an extended blackout is important to your business, you have probably already investigated generator technology. Just don't run the generator indoors; it's noisy and probably fatal. If you have a large installation, you probably have a rather large diesel or propane generator parked outside somewhere hooked in through an automatic switchover arrangement. It doesn't get any better than that, as long as the equipment is kept in good shape and you have plenty of fuel (I know of one wireless ISP that had a monster propane-powered generator for their main broadcast tower that failed to start during a Fall storm power outage because they didn't keep a good eye on their battery, and it was completely dead).

If you live or die on your phone service (or your network itself), you should stock replacement parts for everything in that network: routers, switches, hubs, specialized hardware firewalls, edge servers, UPS's, telephone handsets, and so forth. Any good NOC that serves a large customer base does this (and their switches can be very expensive). If you are a fanatic, you can even run dual "failover" networks inside your organization, but for most situations that's massive overkill.

Before you go overboard, remember the disaster phone number feature in your VoIP system if it has one (more on that later). You may be able to live with a certain amount of risk, just as you used to live with the possibility that your old-fashioned POTS might fail. Always balance cost of risk against cost of avoidance. After all, you acquired your VoIP system for its features and lower costs. Right?

Now, how about the things beyond your control?

• Your ISP
• The Internet itself
• Your VoIP service provider's NOC and interface

Your ISP is like your telephone company. In fact it might be your telephone company if you subscribe to DSL. If you've chosen a top notch ISP, they probably already do the same things you should be doing in your office, to protect their assets and service. In addition, they likely monitor their networks continually to make sure problems are handled as quickly as possible. Do your homework here. Don't be afraid to ask questions. At a minimum, they should be doing the same things you're doing within your own organization to insure reliability. Some NOC's (especially high-end web site hosts) go to very impressive lengths to secure their service.

Still, trees blow down on hanging telephone cables and TV cables no matter how good the company is. And careless backhoe operators still break buried cables.

It's harder to interrupt fixed wireless service (microwave radio link between your building and a tower or repeater somewhere) as long as their central "hub" has power and a working link into the Internet. Still, big chunks of ice have been known to fall from further up the tower onto wireless "hub" antennas and destroy them. Also, wet or snow-covered trees can soak up microwaves if they're between you and the wireless "hub".

If your Internet Service Provider (ISP) is questionable, you can subscribe to a backup service with just enough bandwidth to keep you operational. For instance, you could receive 10 Mbps service from a wireless ISP as your primary service and 1.5 Mbps DSL service from your local Telco. A load-balancing switch at the head of your internal network will automatically use whatever service is available. Or, you can just manually plug your primary router into the backup service's modem when disaster strikes.

The Internet is made up of thousands of individual networks connected by dozens of "Tier 1" carriers (such as AT&T, MCI, XO, and so forth). It would be as difficult to kill the Internet, as it would be to bring down the POTS network. So, don't worry. Even a conspiracy of terrorists couldn't do the job short of a widespread nuclear attack (and then you won't worry much about the network anyway).

Your VoIP service provider might go down for scheduled maintenance or have a critical switch problem within their network. Again, the quality of the organization will tell. Some, like Worksmart^TM, have mirrored sites at more than one location. Most have UPS capabilities, generators, and multiple servers in their NOCs.

If your VoIP service provider goes the extra mile, they will probably use more than one carrier to supply their networks (both Internet and POTS), so if one goes down, another will take up the slack. Again, don't be afraid to ask questions.

Still, just like the old POTS providers, the service may be interrupted because of a weak point in the system, for configuration upgrades, or scheduled maintenance (hopefully during "off" hours). Here is where disaster planning can really pay off. And it's easy.

Just have a backup service.

For small businesses, the boss' cellular phone would make a nice backup device. Just designate your backup device's phone number as your "disaster" number using your company "dashboard". As long as the disaster part of your VoIP service provider's system is working, you'll still receive your calls, or at least have them routed to voice mail if your backup device is busy. You can designate a disaster number for each "seat" if you want. Imagine everyone's cell phone as a backup device. Each group you create can have a disaster number, possibly the cellular phone of the group leader or manager.

So, you see that you can actually have a fairly large disaster network as long as your VoIP service provider has this feature and is operating properly.

For large businesses or call centers, you can retain a couple of "regular" phone lines on a small "hunt group" or subscribe a minimum number of "seats" from a competing VoIP service and designate its DID (phone number) as your disaster number from your main system. Using another VoIP service assumes that internal and external networks are still working and the problem lies with your VoIP service provider. So think carefully about this to see if the expense is commensurate with the risk. I'm not wild about either of these options, but your situation may be just right for one or the other.

Security

Actually, a properly configured VoIP system is harder to "listen in on" than a POTS phone. Most VoIP service providers encrypt conversations from your telephone handset (or adapter) and only decrypt it when it enters the "regular" phone system at their interface in their NOC. The encryptions used are often proprietary and strong (similar to AES or 3DES). Remember to enable the feature when you set up your handsets assuming that your VoIP service provider supports it.

Summary

Like any complex system, VoIP telephony has a number of weak spots that can interrupt the service, especially during storms and other disasters. Careful planning can reduce your risks. The amount of effort you put into reducing your risk will depend upon the value you place on the service (is it life or death for your organization, or just an annoyance).

The most likely problem will be a power outage, and UPS technology can be a very cost-effective way of avoiding the problem (and electronic equipment lasts longer when hooked up to a UPS because the equipment is protected from spikes and brownouts).

Beyond that, your risk avoidance becomes a matter of providing alternative communications capabilities. It can be as inexpensive as using existing assets, such as cellular phones, or you may be more comfortable with more expensive "backup" such as scaled-back POTS service or dual VoIP providers.

In any case, VoIP can be as (or more) reliable as plain old telephone service. It's all a matter of planning.

Allan Kalar is the Director of Technical Services for Viking Waters (www.vikingwaters.com). Viking Waters is a North American reseller of Pandora's Worksmart^TM VoIP service, as well as being an APC^TM UPS dealer. Al is Viking Waters' main contact for sales and support of both products.