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September 2007 | Volume 10 / Nuber 9
Feature Articles

WiFi Telephony Gets Pervasive

By Richard Grigonis

WiFi telephony, once exotic, continues to become commonplace, first in vertical markets such as healthcare, retail and manufacturing, and now in the enterprise. The only question that remains is whether workers will be using dual-mode cellular/WiFi devices that can roam seamlessly between those two wireless worlds, or if a given company’s investment in existing infrastructure dictates that their corporate communication system act more like a “mash up”, with calls and multimedia being forwarded to separate devices as needed. This appears to be more a matter of “corporate culture” and how quickly legacy equipment is to be replaced.

With all the hubbub over WiFi telephony, people forget that WiFi itself is simply a wireless extension to Ethernet, with access points acting like Ethernet LAN jacks. Unlike the LAN card in your desktop PC, however, a WiFi phone can roam about to the point where Quality of Service (QoS) can degrade, given that more than one device can access an access point simultaneously and given WiFi’s limited range of a few hundred feet. Moreover, Ethernet itself was never that great in the QoS department, since its Medium Access Control (MAC) layer protocol for sending and receiving packets (or “frames” in Ethernet parlance) has, despite a few improvements since the 1970s, been a relatively primitive contention-based process that doesn’t allow for QoS.

That’s one reason the Wireless Multimedia Extensions (WME), now known as WiFi Multimedia (WMM), were formulated by the WiFi Alliance trade organization, based on the WiFi QoS enhancement specification (IEEE 802.11e). WMM changes the Ethernet MAC layer to enable a prioritization scheme (vaguely reminiscent of Cisco’s MPLS for larger wireline networks) that defines four types of traffic: Voice (e.g., VoIP on WiFi phones), Video, Best Effort, and Background. WMM doesn’t guarantee throughput however, since, unlike your friendly local Ethernet wall jack, your WiFi-enabled phone can easily wander away in the hands of a user and disappear from the network entirely.

The IEEE 802.11e standard also implements a QoS feature normally found on the PSTN - admission control to the network. During certain time intervals a given access point has total control of the medium and determines which mobile stations can transmit. Also known as WMM2, a similar mechanism called the Point Coordination Function (PCF) was in the original 802.11 MAC layer specification, but few vendors ever implemented it. Also lumped under WMM2 is an additional feature, Unscheduled Power Save Delivery (UPSD), which conserves handset batteries by allowing them to “sleep” periodically.

Wither WiFi?

Amazingly, at the end of 2006, Dan Jones, writing at Light Reading’s Unstrung online enterprise wireless publication, boldly went where no pundit had gone before, predicting that the WiFi handset market wouldn’t survive through 2007. He believes that dual-mode cellphones made by such companies as Motorola, Nokia and Samsung will displace dedicated WiFi handsets. Of course, that didn’t stop SpectraLink (, just prior to their acquisition by Polycom, from introducing their NetLink 8000 Series Wireless handsets a few days later, available with 802.11a/b/g radios - consumers are accustomed to 2.4 GHz “b” and “g” WiFi, but enterprises appear to be moving to the additional, clear 5 GHz channels afforded by “a”. (Still, many existing WiFi phones work with “b” such as ZyXEL’s WirelessIP5000 VoIP Phone, or with “b” and “g”, such as ZyXEL’s Prestige 2000W v2 WiFi VoIP Phone.) Now with the Polycom acquisition, SpectraLink has an even better set of sales channels.

As Ben Guderian, Vice President of Marketing for Polycom’s SpectraLink division says, “The acquisition by Polycom occurred March 26th. That went smoothly because there wasn’t much overlap between the Polycom products and ours, and there are some really great opportunities for synergy to bring wireless products into the Polycom VoIP deskset business.”

“Of course, even prior to the Polycom discussions, we were identified as a company that went after the SMB market and telephony service providers. With Polycom we have a ready-made channel to go after that. We haven’t done a whole lot yet regarding dual-mode because we still have a lot on our plate in terms of satisfying the mainstream WiFi telephony market which still consists of the vertical markets. And of course we do a lot of business with our OEM partners.”

Just prior to the Polycom acquisition of SpectraLink, there occurred a similar event, Motorola’s acquisition of Symbol Technologies (, thus furnishing Motorola with a ready-made enterprise mobility business. Symbol was always known for its voice-enabled mobile computing devices catering to the needs of such vertical markets as retail, warehousing, logistics and transportation, government, healthcare and manufacturing. For example, consumers visiting upscale retail outlets may encounter Symbol’s MC17 consumer shopping terminal that hastens the shopping checkout process, locates items, checks pricing and finds complementary products and personalized promotions and recommendations. In the enterprise, Symbol’s RFS7000 Wireless Switch has voice-centric features and capabilities, supports Motorola’s Wi-NG architecture for campus-wide roaming across subnets, and offers expanded failover capabilities, enhanced quality of service (QoS) and increased voice capacities.

Symbol offers such QoS-enhancing features as WMM, WMM2 and SIP Call Admission Control that allows enterprises to define the number of voice calls that can connect to an access port to prevent overload and degradation of service. Voice prioritization can be done even with packets originating from legacy voice solutions that don’t support WMM. Symbol’s implementation of Multi-BSSID establishes a separate virtual wireless LAN for voice traffic, improving voice performance and eliminating the processing of unnecessary messages by mobile devices, improving battery cycle times and overall battery life expectancy.

Moreover, since security has been such a problem with WiFi over the years, Symbol offers their Wireless Intrusion Prevention System (Wireless IPS) to protect corporate wireless network infrastructures, mobile devices and wireless traffic from external threats. Wireless IPS enables you to proactively monitor your wireless network for weaknesses and fix them before a hacker intrudes. It can also help with eliminating “blind spots” in your WiFi coverage. The plug-and-play Wireless IPS has a distributed and centralized architecture, and performs its analytic duties while consuming minimal bandwidth.

Security upgrades have also been done to the Sipera IPCS 520 from Sipera Systems ( It’s a pizza box-sized device that complements existing security gateways and firewalls with application-level intrusion prevention, denial of service (DoS) prevention, troubleshooting, network-level security and spam/voice spam filtering. The Sipera IPCS 520 can be deployed in active mode in the path of subscriber traffic or passive mode on a mirrored port. It can be deployed without an IP address as a “bump in the wire”, with no network configuration changes required. It’s designed to enhance security for those service providers offering services based on the Session Initiation Protocol (SIP), IP Multimedia Subsystem (IMS) or Unlicensed Mobile Access (UMA) technologies. The Sipera IPCS 520 supports 100,000 users and 10,000 simultaneous sessions with 2Gbps of throughput in IDS/IPS mode.

To secure dual-mode phone service, the Sipera IPCS 520 serves as an IDS/IPS security solution at the service provider edge while enterprise-class Sipera IPCS products are deployed in the enterprise “Demilitarized Zone” or DMZ (a server or small subnetwork situated between the trusted internal corporate LAN and an untrusted external network, such as the Internet), allowing secure integration of dual-mode phones with the corporate IP PBX.

Consumer WiFi Telephony

Although WiFi Telephony’s early successes were in the vertical market workplace, residential users of Vonage’s VoIP service can now avail themselves of “Vonage WiFi Phone” which is made by UTStarcom ( and accesses the Vonage service by connecting to wireless Internet WiFi hotspots worldwide at no additional cost. The device provides a 200-entry phone book, speed dialing, a call log, and various ring tones.

And speaking of UTStarcom, their latest residential WiFi handset is the F3000. With its clamshell design, it supports 802.11b/g, SIP, SDP, RTP, DHCP and TFTP, as well as the usual call feature set (three-way calling/call waiting, call rejection/redial/mute, call transfer/call forward, etc.)

Another interesting WiFi handset is the Ascom i75 by Ascom ( fits wireless telephony, wireless messaging and a wireless personal alarm into a single device for users in manufacturing, health care, retail and “secure establishment” segments. Part of a whole wireless system portfolio, it’s compatible with the Cisco Compatible Extension (CCX) version 2. If you break your handset, Ascom’s Virtual SIM feature allows you to transfer your personal profile and settings from a central server to another “system-associated” handset. Ascom’s VoIP Gateway allows smooth integration with a circuit-switched PBX or public switched telephone network to provide voice communication between Ascom VoWiFi handsets and any other phone in your organization. The VoIP Gateway can handle up to 1,000 Ascom handsets and comes with T1 or E1 interfaces and 60 simultaneous speech channels to the PBX. Protocol support includes QSIG, NI-2, 5ESS, DMS 100, and the E&M CAS trunk protocol.

Of course, HSDPA (High-Speed Downlink Packet Access, also known as High-Speed Downlink Protocol Access) may finally get going at full throttle with cellular services in the form of so-called “Evolved HSPA” (also known as: HSPA Evolved, HSPA+, I-HSPA or Internet HSPA) the 3G mobile data protocol defined in 3GPP release 7, it provides theoretical data rates up to 42 Mbps on the downlink and 11 Mbps on the uplink. If that happens, perhaps small businesses will replace LAN wall jacks with docking stations for their cell phones! IT

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

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