Here are lessons testers have turned into tips for ensuring you make ultrasmart buying decisions.
1. Weigh the Session Initiation Protocol (SIP) factor. VOIP gear either supports the standard SIP or uses a proprietary format. "SIP-standard gear gives you lower costs and good prospects for multivendor interoperability," says Ed Mier, president of testing lab Miercom. "But it's still 'some assembly required' in many cases and offers fewer features because the standards are still being finalized. Proprietary alternatives give you single-vendor ownership and more features, but higher costs and limited multivendor interoperability."
2. The more trunking support, the better. Ask VOIP equipment vendors what carrier services they work with over SIP trunking, then "seriously consider the vendor that supports the most," Mier says. "You will save big time over the next year in replacing expensive channelized T-1 trunks."
3. Check bandwidth controls. "A key component of VOIP quality comes from your ability to control VOIP bandwidth consumption," Mier says. Look for gear that supports automatic G.729 vocoding over WAN links and provides good QoS and detailed call-admission control.
1. Test for "moves, adds and changes." Have prospective vendors walk you through the steps to add a new hard phone and a new soft phone user, including setting up voice mail. "If it takes more than 5 minutes and/or five screens of data entry, consider another vendor," Mier says.
2. Check QoS monitoring. "Find out if the vendor's management pack includes any options or supports third-party packages for tracking [QoS]," Mier says. "That way, you can investigate complaints of poor call quality."
3. Beware SIP-based management. "There are many advantages to a SIP-based IP PBX," Mier says. "But management likely isn't one of them." With SIP's ability to mix and match multiple vendors' equipment comes multiple management interfaces -- one for call control, another for phone sets, another for gateways and so on. "Know what you're getting into," he cautions.
1. Don't minimize power decisions when planning for wireless LANs, especially if wireless VOIP is involved, says Tom Henderson, managing director of ExtremeLabs. "Keep wireless VOIP alive by choosing access points that support Power over Ethernet, and connect the hubs and switches to [a UPS]," he says. "A UPS/PoE infrastructure can usually withstand brownouts and other conditions that might otherwise cause VOIP outages. It's also more convenient to use PoE when hanging access points in false ceilings where power outlets are at a premium or might not exist. A few access points have integral batteries, but we don't recommend them."
2. Don't skip the survey. "A Wi-Fi plan requires examining the air space with a Wi-Fi analyzer before buying and deploying access points -- no matter how clever the access point or how powerful its signal or antennas are purported to be," Henderson says, noting that strange things can block signals, and co-channel interference can rob you of your investment.
3. All rogues are not alike. Check whether your vendor's rogue containment feature can distinguish between different types of rogues, says David Newman, president of consultancy Network Test. "If you're Starbucks, you want to kick unauthorized users off your network -- but not off the McDonald's network next door."