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Setting Up the Right VoIP Cabling Topology

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Setting Up the Right VoIP Cabling Topology

January 03, 2014

  By Mae Kowalke, TMCnet Contributor

Plug it in and it works. That’s part of the charm of VoIP phones.

That’s the general perception, at least. In reality, getting VoIP to work right is a little bit more nuanced. That’s partially because many VoIP installations are run over the same cabling system that is used for Web traffic.

If too much of the network is being used by other devices, call quality suffers; this is one of the reasons that VoIP, while able to achieve a much higher quality than analog calling, often sounds worse in practice than what came before. In these cases, there simply isn’t proper prioritization in place for the VoIP data stream, which needs low latency and the right amount of bandwidth, whereas other IP applications often have a greater tolerance for latency and data bottlenecks.

There are three IP telephony architectures that can be used: The dual-port method where both a VoIP handset and other devices share the same data connection; a softphone system where VoIP bypasses a handset and is conducted through a more general device such as a laptop; and separate lines, where a VoIP handset and other devices do not interfere with each other.

While any of the three can work, it is strongly recommended that businesses go with the latter option, dropping one cable for voice applications and the other for data applications. This makes troubleshooting easier, ensures higher quality, enables businesses to send power along the voice applications cable, and separates voice and data functions.

To properly set up an office for VoIP, it also is good to consider using a Category 6 cabling system instead of the standard Category 5e. Cat 6 is a new implementation, and it offers better speeds and signal to noise ratio. Most manufacturers have designed their solutions around Category 5e, but once the convergence of voice, data and video is complete, there should be a shift to Cat 6. So installing Cat 6 from the start makes sense.

In addition to separating lines and using Cat 6 cabling, businesses setting up their cabling topology for VoIP should make provisions for prioritization and power over UTP.

Today’s telephones are fully functional during outages, but emergency power units are not available for most of the data network equipment. As a result, VoIP requires a structured cabling system that ensures that backup power gets to each handset—sending power over UTP is thus a critical VoIP technology.

So is prioritization. Often there is enough bandwidth for VoIP calls, but due to a lack of awareness on the router’s part, VoIP data streams are not issued the necessary bandwidth. This is another reason to separate voice and other data cabling—it is easier to prioritize voice if it is on its own cable.

Edited by Blaise McNamee
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