By Stephen Withers
An estimated one-third of businesses are already using WiFi (wireless fidelity) but only a tiny proportion—optimistically three to five percent—are using it for voice communications, according to Telsyte analyst Warren Chaisatien
Voice over Internet Protocol (VoIP) over WiFi “is not all that attractive yet”, he says, adding that large corporate and government organisations with 500 to 1000 people at a single location can have a private cell installed by their chosen carrier. This gives free calls within the cell. Smaller users can usually get very cheap rates (in some cases free calls) between their mobile phones from carriers such as Vodafone and 3.
WiFi handsets are mainly used at the moment in medical, warehouse and factory settings, says Chaisatien. They’re also attractive for “corridor warriors” (someone that spends more time between meetings than at their desk) in corporate campus environments.
Tony Warhurst, director of business development Oceania at Zultys Technologies identifies senior partners and executives at legal and accounting firms as prime candidates, as they want to be easily contactable while on premise without the cost of calling from mobile phones. Technical staff will also often carry a smartphone or a PDA that can run a softphone giving VoIP- over- WiFi access.
IBM’s Vocera wireless VoIP product is aimed primarily at hospitals, while Zultys recently won a contract with an RSL club that wants to give security and other staff wireless handsets to combine the functions of existing pagers (alphanumeric display), walkie-talkies (push-to-talk convenience) and mobile phones (VoIP).
“We see voice as the killer app for wireless. The economic benefits are just enormous.”
David Humphries,
Aruba
WLAN infrastructure
If you’re going to do VoIP over WiFi it’s important to get the wireless infrastructure right.
Opinions vary about the need for a site survey. Damian Stock, consulting systems engineer at Symbol, says it is “absolutely critical” and recommends a commissioning survey to fine-tune the network after installation. If the number of access points is over-generous for the area (perhaps to allow for a high device density) it is important to adjust the power levels so that no more than three cells overlap at any location or performance will be degraded.
“Practically all of our voice over IP implementations have had a site survey done first, and a commissioning survey to adjust power,” he says.
Warhurst says a competent provider should be able to recommend a workable installation based on the floor plan, but a large multi-floor deployment usually needs a survey to get satisfactory results. “I would certainly recommend it if you’re using wireless as your major network,” he says.
Mark Little, head of product and solutions engineering at AAPT has a similar view: “This will depend on the layout you’re trying to achieve coverage over. Small open-plan areas do not require a great deal of effort, however, providing adequate coverage over larger sites or where concrete is involved would benefit from a site survey.”
Chris Brown, convergence business manager for Asia Pacific at 3Com, says it largely depends on expectations. If an organisation is happy with the idea of making adjustments after installation it might be worth skipping the survey and perhaps spending some of the savings on a few more access points. In a large deployment, or if the expectation is that the network will work perfectly first time, a site survey will improve the customer experience and help with cost containment. Either way, computer aided design-based tools can reduce the cost of a survey. In addition, a site survey can help an organisation to be a good neighbour by reducing WiFi leakage into adjacent premises.
Traditional access points don’t handle roaming very well due to the need to reauthenticate each time a device associates with a different access point. This isn’t a major inconvenience for notebook users but in these circumstances VoIP dropouts are “almost inevitable”, according to Brown.
The answer is to use wireless switching, which moves authentication and management to a central switch. The cheaper access points offset the cost of the switch—installations using ten or more access points should see a net saving from this arrangement.
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