There's plenty to like about VoIP. There's also plenty to hate. While VoIP vendors are good at touting the former, they tend to ignore the latter. Here, then, are six "gotchas" picked up over the years of deploying and reporting about all things VoIP-related--none of which will eliminate the technology from your business' consideration, but all of which must be accounted for when you consider the technology.
1. Reliability headaches. It's a fundamental axiom of manufacturing engineering and just plain common sense that all things being equal, the product with fewer parts will be the more reliable one. If that's true, then VoIP starts out with a significant strike against it. Unlike digital networks that just consist of telephony switching equipment, cabling, and telephones, VoIP systems brings the additional complexity of the underlying data network. The choices made at those layers, independent of the VoIP network, will make or break a voice system. Mess up on the VLAN or QoS settings of your switch or router and watch voice quality tank the next time a virus-infected PC spews junk onto the network. Reboot a router or switch and watch voice calls drop. Lose power and an improperly designed data network will send voice to you-know-where.
2. Hidden costs. A two- or three-year-old 100Mbps or even 10Mbps infrastructure may have a fair amount of gas left in the tank, but the conversion to VoIP will force most companies to buy new data equipment and even new wiring. They'll need switches that implement 802.1p (MAC-layer QoS) and 802.1q (VLANs). If availability during power outages is necessary, then those switches will likely need to be equipped with inline power (802.3af). All totaled, expect new edge switches to run at least $68 for a 48-port switch. A VoIP-enabled router, like HP's ProCurve Secure Router 7000dl, will run $1,173 to $2,303 depending on the configuration. This says nothing for fees relating to network design, installation, and maintenance contracts.
3. Plenty of insecurity. VoIP bigots will remind you that wiretapping in the PSTN is a technically trivial task for any accomplished technician. What they won't mention, however, is that while the PSTN carries its own vulnerabilities, the VoIP world must contend with a potent combination of global accessibility and simple-to-use hacking tools. Users otherwise ignorant of the ways of wiretapping or war dialing can easily download applications such as Cain and Abel or Trinity and snoop on phone calls or launch a massive distributed denial of service (DDoS) attack that disables a phone number. Companies looking at deploying VoIP must plug those holes in their data network if the voice network is to be secure.
4. Talking underwater. Digital telephony is nice and neat. Pick up the telephone, dial, and talk. Voices never sound as if they're coming from handsets filled with seawater. Yet run VoIP over a poorly engineered network and you'll find warbled voices, echo, and just about any other type of distorted voice condition.
5. The saga of the softphone. Some aggressive VoIP providers will argue that the PC can be used as a telephony replacement. Just buy a USB headset, load up a softphone, and voila! Companies can save the cost of their digital handsets. However, the fact is that most companies will find their softphone performance to be erratic. The combination of Windows XP and PCs have yet to provide an effective way to prioritize voice threads, allowing applications to hog a PC's processor and wreak havoc with voice calls. Echo cancellation is difficult to tweak when the two softphones on either end of a call come from different manufacturers, or when a softphone communicates through a PSTN gateway to a regular phone. Much of that might change when Vista ships and with improvements in processor design.