Intranet Telephone System

On January 19, 1998, Symbol Technologies (later part of Motorola, Inc.) and Cisco Systems announced that they had combined the Symbol Technologies’ NetVision™ wireless LAN handset and Cisco 3600 to provide a complete wireless local area network telephone system based on Voice-Over-IP technology.

The handset uses a wireless LAN (IEEE 802.11) infrastructure and a voice gateway via Cisco 3600 voice/ fax modules. The system conforms to H.323.

"I believe that this is the first wireless local area network telephone based on this technology" -- Jeff Pulver

Seamless roaming via Symbol’s pre-emptive roaming algorithm with load balancing.

Claims each cell can accommodate ~25 simultaneous, full-duplex phone calls. Ericsson partnered with Symbol, using Ericsson’s WebSwitch2000.

Transcript

[slide44] Now, Jeff Buller described this technology used by combining that Cisco gateway together with wireless LAN as the first wireless local area network telephone technology. And basically it was introduced by a company called Symbol Technologies. And Symbol Technologies' main business at the time was barcode scanners. And they had a customer, [Crescent Drugs,] McKesson Drugs in the U.S., and they built an arm-mounted barcode scanner. And the idea was that a customer places an order, the order would get transmitted to someone who would fulfill the order from the warehouse. And they were delivering pharmaceuticals. So someone had a prescription, the person would go in, and they pointed the barcode scanner at the bin, it scanned it to make sure it was the right drug, they would get out the right dosage, put it in the bin, send it off. The problem was sometimes they'd be out of whatever it was that they were supposed to get. So they'd have to call someone else in the warehouse, hey, it's time to refill bin number blah blah. So they needed a phone. So they said, hey, we've already got wireless LAN connectivity to this thing, we've got it displayed there, we know what it is, why don't we just build it all into one system? So they integrated voice with their data system. They showed they could accommodate 25 simultaneous full duplex calls across the wireless LAN. Subsequently, I had two students who showed that they could actually double that number by being clever about how you allocated the resources, because the advantage is that if you can fit more calls across a given bandwidth, what happens? We're happy because we avoided the collisions, because instead of contending for the channel, they would know, aha, it turns out, as we will see when we look at RTP, we produce the IP packets periodically, so we know when they are. And if everyone else is producing packets periodically, what can we do? We can produce a schedule, so that by aligning the schedules, instead of fighting for the resource, we know, oh, she's first, he's next, he's next, she's next, etc. There's no contention at all. So we can actually support even more simultaneous calls.