Are wLANs VoIP-Ready?

VoIP software company HelloSoft is holding a special press shindig next Monday — a pre-VON warm up. The San Jose-based startup is inviting members of the fourth estate to shmooze with HelloSoft execs and take the company’s seamless cell-WiFi handoff technology for a spin.

Moving a call seamlessly between cell and VoIP networks is certainly sexy. But before you can move the call between the networks, you first need the capability to make a VoIP call over a WiFi network reliably.

So I called up Meru Networks, the Sunnyvale networking company that specializes in wireless LANs for organizations like college campuses, hospitals and corporate campuses, to ask some experts what it takes to assure that we’ll be able to use HelloSoft’s technology when it hits retailer shelves.

Although Meru isn’t in the metro WiFi business, the challenge is nonetheless the same.

“What customers want is guaranteed application delivery on a secure network that supports high quality voice, hi-speed data, streaming video,” says Michael Tennefoss, Meru Networks VP of Marketing. “If they have it on a wired connection, they want it on the wireless network.”

But when you peel back the technology onion, delivering that quality of service isn’t so simple.

“The first issue is establishing and maintaining the connection,” Tennefoss says. “When you’re walking around on a WiFi phone you have a problem you don’t have at home when you’re in close proximity to your wireless router. You have the problem of how the call moves across access points.”

There are two ways to do this. One method is where the device — telephone, laptop — makes the hand-off decision between access points based on signal strength. This is used in many legacy wireless LANs.

The other method, used in the cell phone world, makes the handoff decision centrally. This is the method that Meru favors.

When the traffic is voice, Tennefoss says, “You have to think of a client/server architecture. You can’t leave it us to the device [to determine the access point] because it affects others. To make it work you need to know what applications they’re running. You need a parent to make sure they play well together.”

Then you can balance the load based on the application. For example, email doesn’t need as much radio power as a voice call. “You have an intelligent handoff based on what the user is doing,” Tennefoss explains.

Meru has no small amount of experience delivering mobile VoIP in some challenging environments: hospitals (lots of metal), college campuses (indoor/outdoor environment), and corporate campuses.

One of the lessons of this experience is that existing wireless LANs can’t be relied on to deliver the next generation of application mobility, Tennefoss says. “The wireless infrastructure that may have been put in for email can’t accommodate these gadgets. Some can only handle four calls at a time. You can’t have that in a hospital.”

And as wireless becomes the de facto connection, it doesn’t take Nostradamus to predict that we won’t tolerate those limitations anywhere, opening more doors for the Merus of the world.