Electronic Design

VoIP Requires DSP Algorithm And Telephony Standard Know-How</A><BR><FONT CLASS=body11>Sponsored by: <A HREF="http://www.freescale.com" TARGET=_blank CLASS=body11>FREESCALE SEMICONDUCTOR</A></FONT><A>

The montage of signal-processing requirements and signaling protocols that allow data networks to move voice packets necessitates alliances to leverage specialized knowledge.

It's very tempting to enter the impressive and growing voice-over-packet (VoP) market (voice over frame relay, voice over ATM, and Voice over Internet Protocol) by developing a product or service. But first, familiarize yourself and your staff with dozens of standards related to telephony and network signaling. Then, learn all you can about digital signal processing so you can implement the many signal-processing algorithms needed to deal with voice compression, echo cancellation, noise reduction, and many other issues.

Why All The Hubbub About VoP?

VoP offers many economic advantages over standard copper-based telephony, both from equipment and wiring standpoints, as well as from a usage cost model. Because the equipment leverages standard Ethernet LAN technology as the medium (both wired and wireless), costly PBX systems and the associated twisted-pair wiring for each handset can be eliminated. Instead, Ethernet cables with switches or hubs, or even wireless Ethernet systems, can replace the point-to-point wiring with what basically looks like a single cable going around the facility.

Although the initial cost of IP-capable telephone handsets is significantly higher than the cost of analog/digital handsets, IP phones have many benefits. For instance, the ease of tapping into the network and the flexibility of assigning phone numbers to IP addresses rather than to physical wires make it easy to move extensions around the facility without massive rewiring, lowering maintenance costs. Embedding a wireless network connection in a cell phone even lets you go on and off the network to obtain the lower-cost VoP call services while connected to the network and use the standard wireless cellular network while out of range of a wireless network access point. The trick will be the software in the phone that manages the connections and handoffs between the two systems.

In fact, you can move the IP handset to any location on the network and still be reached. That's because the packets being sent are routed to a phone number that is actually translated into an IP address rather than a physical location. In some ways, that makes an IP handset a "world" phone because IP addresses are global in nature. You should be able to plug an IP handset into an Ethernet jack anywhere in the world and still maintain your phone number as if you were in your office. When someone dials your phone number, the system translates that into an IP address and locates your phone if it's plugged into the network.

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TAGS: Digital ICs
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