Outages and Ethernet

Step 2: Prevent Outages

IP telephones must work even when the power goes out, just like wireline phones. This will require UPS (uninterruptible power supply) support for every piece of network equipment that handles voice traffic.

Most enterprises currently provide this kind of backup power only to servers and the central PBX. In a voice-over-IP implementation, however, every switch and router between the telephone handset and the iPBX must have reliable backup power.

This will likely mean an extensive investment in wiring-closet UPSes.

Step 3: Power Up with Ethernet

Perhaps the most significant change in the wiring closet is a shift from unpowered to powered switches. In a power over Ethernet (POE) environment, electricity is supplied to the handset from either a powered switch or a mid-span power injector, a device that looks like an Ethernet switch and adds electricity to the network wire pairs to support POE.

eWEEK Labs recommends using powered switches rather than mid-span power injectors to conserve rack space and ease configuration of the new system.

The POE standard also makes it possible for information technology managers to confidently install IP telephone handsets without regard to the manufacturer of the power sourcing equipment. These handsets work in much the same way as traditional telephone receivers, drawing power over the same cable as the data signal. POE significantly eases handset installation by eliminating the need for technicians to hunt down open outlets.

At the most basic level, voice-over-IP equipment requires properly installed Category 5 cabling. Among other things, I.T. staff must ensure that run lengths, connectors and terminators meet specifications. If there is any doubt about the quality of the network cable or its installation, use a testing tool.

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