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November 2007 | Volume 10/ Number 11
Feature Articles

Taming the Wild World of WiFi Telephony

By Richard “Zippy” Grigonis

WiFi telephony originally conquered the vertical markets, particularly healthcare, and is now starting to move onto new higher-bandwidth 802.11n platforms, where it will compete with femotcell technology that scales down cellular voice and data services to tiny base stations having WiFi-like hotspot coverage. Re-engineering and testing data networks to ensure voice compatibility and high quality of service will be of utmost concern.

For any readers who have been living in the Carlsbad caverns during 2007, Polycom acquired SpectraLink Corp., ( finalized as of March 26, 2007. Polycom was eager to get its hands on SpectraLink’s superlative WiFi phone technology, such as their 900 MHz Link WTS, and NetLink wireless phones for legacy PBX systems and enterprise IP networks.

Ben Gurderian, SpectraLink’s Vice President of Marketing, says, “The Polycom acquisition went smoothly, because there wasn’t much overlap between the Polycom products and ours. There are some really great opportunities for synergy, to bring wireless technology into the Polycom VoIP deskset business. Many of our new opportunities are in that direction. Even before the acquisition, we were recognized as going after the SMB and telephony service provider markets. With Polycom, we now have a ready-made channel to go after them now. There are a lot of great things that we can do. We have a lot on our plate just in terms of satisfying the mainstream WiFi telephony market, which still consists of vertical markets. And of course there’s a great deal of business done with our OEM partners.”

“We launched our latest generation WiFi handsets in January 2007,” says Guderian. “Since then our two major OEM partners, Nortel and Avaya, have booth launched their respective versions. If you hold them next to each other you can tell that they are the same, but a great deal of customization goes inside those handsets; in particular to support their proprietary voice protocols. There’s always a lot of work to do to fine-tune the handsets to make them work well with call servers from companies such as Nortel and Avaya. We also have an Alcatel Lucent model in the works - they’re already an OEM partner, and any day now they’ll be launching their next-gen version of our latest handset.”

“As we move to the Polycom channel, we’ll be transitioning from providing the more highly customized proprietary VoIP protocol support to much more standards-based SIP support.”

Lending a Helping Hand

For such an overly-dynamic, almost mercurial kind of wireless network, testing and monitoring are highly important. AirMagnet ( was a company that saw an opportunity here, and now over 6,000 businesses worldwide operate better-performing wireless LANs thanks to AirMagnet’s planning, troubleshooting and monitoring solutions. In particular, AirMagnet has recently released an innovative troubleshooting device for Voice-over-WiFi, the VoFi Analyzer.

AirMagnet’s Director of Product Management, Wade Williamson, says, “I see the market as being quite vertically focused, but growing out to be a bit more horizontal. The big verticals are healthcare, first and foremost, then we see some deployments in retail and even manufacturing. The healthcare vertical is especially a good industry ‘litmus test’, because you have a critical use of voice in probably the most challenging wireless environment you can imagine. Once we can prove that WiFi voice really works well in that environment, then we can deploy it anywhere, because in healthcare facilities there are obstructions in X-ray rooms, electromagnetic equipment that causes interference, old and heavily constructed buildings, and voice applications that must work correctly if nurses and doctors are going to be at the right place at the right time.”

“We first help healthcare centers redesign their networks for voice,” says Williamson. “That’s one of the big absolutes. If you’ve got a big network that you’ve been using for data and you’ve got ‘guest access’ and you may pull a file down here and there, then that wireless LAN you’ve designed may be just fine for those limited purposes, but it may fall way short of what you want to do with voice in that organization.”

“Once you’ve made the jump to a real-time application such as voice, then you’ve gone to something that’s far more critical,” says Williamson. “There’s a different WiFi design spec for voice. You’ve got to ask how many access points [APs] you need. What power should they operate at? That’s actually one of the most prevalent things we’ve seen folks challenged by, regardless of whether they’re using Polycom SpectraLink phones or Cisco Vocera communicators.”

“Typcially, when people nail up a data network,” says Williamson, “they ramp their APs’ output to 100 milliwatts. But a phone that outputs anywhere between 5 and 20 milliwatts could give you an imbalance wherein the phone receiving the call can hear it just fine, but it doesn’t have the power to send a signal all the way back to the AP. So there are many things to ponder design-wise when building out a wireless LAN, and are really making it fully designed for voice.”

“The ‘next step’ is how to troubleshoot that,” says Williamson, “and at this point we’ve done something fun and interesting. We’ve built an analyzer designed to scrutinize WiFi traffic in the air that’s encrypted. It can tell you, first, what traffic is voice and what traffic is data. For voice traffic it can give you a MOS (Mean Opinion Score) for it and then tell you what the problem is. That concept is revolutionary because if you think of traditional VoIP call analysis, you typically must have access to the protocol stack. You’re going to look at unencrypted Ethernet frames and then piece them all back together and then go look at how the protocols are fitting back together. Being able to do that on encrypted traffic in a wireless LAN is really important, because it harks back to one of the fundamental differences inherent in wireless - you’ve got to assume that all the clients are encrypted and if you tell the IP staff that, ‘Wow we’ve got to turn off all of the security devices so I can figure out why this call is going bad’, well, that’s just not an acceptable statement.”

“Fortunately, that’s what our analyzer is built to do,” says Williamson. “It’ll piece all of the traffic and communications between phones and APs back together and tell you which calls are having problems and then what the cause of each type of problem is. Is it a roaming problem? Is it something on the client side? Is it an RF issue? Is it a misconfiguration in the AP? Or is it something that’s happening way back on the wired side? And with our latest release, the VoFi Analyzer can now integrate not only the information it’s getting from the air, but also the data received from the phones themselves as well as the wired side. SpectraLink phones in particular have the ability to send SysLog information about what the phone is actually receiving at its end. We can correlate that with what our device sees in the air.”

Williamson adds: “We can lay those metrics side-by-side and say, ‘Here’s what we’re seeing from a third-party observer viewpoint, and here’s what the phones actually are experiencing’. And back on the wired side, we can talk to things like Cisco’s CallManager, and obtain information to see what types of performance and statistics we’re seeing on the wired side. We can tie all of the endpoints together and state, ‘Here’s what we see at both ends and the middle’, and we can give you a really succinct view of what’s going on in the network, and we do it all while the network ‘engine’ is running.”

802.11 Alphabet Soup

At Siemens (, their Vice President of Enterprise Mobility, Luc Roy, says, “We see that the new standard for connectivity within the enterprise is no longer wired Ethernet and it’s not conventional WiFi 802.11a/b/g. It’s becoming 802.11n. Not every enterprise will require it, but in talking to many customers, we see 802.11n as becoming the real wireless standard. Ironically, 802.11n is not officially a standard yet, but that’s where things are going. Once you’ve implemented it, there’s no cost associated with it except for maintaining it. 802.11n has sufficient bandwidth to support your organization for many years, even taking into account all of your applications.”

“Wireless voice doesn’t actually require 802.11n - 802.11g should be sufficient - we see ‘n’ taking over anyway,” says Roy. “We see FMC [Fixed-Mobile Convergence] as a real phenomenon, especially in the enterprise. People are looking at convenience and higher productivity, but they’re also looking at cost-effectiveness. If you’ve got a wireless LAN, why would you want to use a femtocell system, or whatever, when you have to pay for the service, and you have to deploy WiFi ‘n’ anyway because it’s becoming the new WiFi standard? That’s why various flavors of 802.11 are firmly rooted in the enterprise and that’s why FMC and its associated dual-mode devices are going to become really popular. That’s where we see the world going.”

“Will dual-mode phones replace all other devices? No absolutely not, but dual-mode will definitely be the technology of choice for enterprise users using cellular phones today,” says Roy. “You’ll still have desktop phones, and single-mode voice wireless LAN phones, such as our Siemens WL2s, but definitely the dual-mode devices are going to serve not just voice but when used with smartphones they’ll be serving a lot of people like we already see in healthcare with doctors wanting dual-mode devices so they can do things with data too.” IT

Richard Grigonis is Executive Editor of TMC’s IP Communications Group.

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