Sample Voice Installations

In many ways, voice installations are quite similar to data installations. The differences are the type of equipment that each end of the link is plugged into and, sometimes, the type of patch cables used. The ANSI/TIA-568-C standard requires at least one four-pair, unshielded twisted-pair cable to be run to each workstation outlet installed. This cable is to be used for voice applications. We recommend using a minimum of Category 3 cable for voice applications; however, if you will purchase Category 5e or higher cable for data, we advise using the same category of cable for voice. This potentially doubles the number of outlets that can be used for data.

Some sample cabling installations follow; we have seen them installed to support voice and data. Because so many possible combinations exist, we will only be able to show you a few. The first one (shown in Figure 1) is common in small- to medium-sized installations. In this example, each horizontal cable designated for voice terminates to an RJ-45 patch panel. A second patch panel has RJ-45 blocks terminated to the extensions on the phone switch or PBX. This makes moving a phone extension from one location to another as simple as moving the patch cable. If this type of flexibility is required, this configuration is an excellent choice.

 
Figure 1: A voice application using RJ-45 patch panels

Tip

Any wiring system that terminates horizontal wiring into an RJ-45-type patch panel will be more versatile than traditional cross-connect blocks because any given wall-plate port/patch-panel port combination can be used for either voice or data. However, cabling professionals generally recommend separate patch panels for voice and data. Separate panels prevent interference that might occur as a result of incompatible systems and different frequencies used on the same patch panels.

The next example illustrates a more complex wiring environment, which includes backbone cabling for the voice applications. This example could employ patch panels in the telecommunications closet or 66-blocks, depending on the flexibility desired. The telecommunications closet is connected to the equipment room via twisted-pair backbone cabling. Figure 2 illustrates the use of patch panels, 66-blocks, and backbone cabling.

 
Figure 2: A voice application with a voice backbone, patch panels, and 66-blocks

The final example is the most common for voice installations; it uses 66-blocks exclusively. You will find many legacy installations that have not been modernized to use 110-block connections. Note that in Figure 3 two 66-blocks are connected by cross-connected cable. Cross-connect cable is simple single-pair, twisted-pair wire that has no jacket. You can purchase cross-connect wire, so don't worry about stripping a bunch of existing cables to get it. The example shown in Figure 3 is not as versatile as it would be if you used patch panels because 66-blocks require either reconnecting the cross-connect or reprogramming the PBX.

 
Figure 3: Voice applications using 66-blocks exclusively

Figure 4 shows a 66-block with cross-connect wires connected to it. Though you cannot tell it from the figure, cross-connect wires are often red and white.

Figure 4: A 66-block with cross-connect wires

The examples of 66-blocks and 110-blocks in this chapter are fairly common, but we could not possibly cover every possible permutation and usage of these types of blocks. We hope we have given you a representative view of some possible configurations.