Here we will give a brief introduction to this new technology as well as describe a few vital considerations when purchasing these systems.

TDM - Traditional Systems
Traditional phone systems operate with a digital signal that is characterized by Time Division Multiplexing, or TDM. Because TDM is so different from data signaling formats, traditional telephone systems operate over a voice network that is separate from the computer network. Generally speaking, TDM systems have provided a high degree of reliability as well as high quality of service.

IP Systems
VoIP, or Voice over Internet Protocol, is more appropriately called voice using internet protocol since the signal takes the form of data packets using internet protocol and may actually be passed through the data network. This new form of telephony will allow for many new features to be introduced; however, in many cases, new features are not the sole justification for investing in IP systems.

Why Purchase an IP System?
One important justification for investing in this new form of telephony is the savings that may result from connecting multiple sites, for example branch offices, over an existing data network instead of a separate voice network.

IP systems use IP trunks or pathways through the existing data network to connect to one another, thereby eliminating dedicated voice services between sites and eliminating the monthly expense of connecting long distance calls between sites.

Offsetting this reduction in cost, the bandwidth for IP trunks in the data pipelines between sites may need to be increased somewhat to allow for voice traffic.

Single site businesses may achieve savings with VoIP by consolidating voice and data networks and simplifying the maintenance of telephony systems. Certain companies may want to have the latest technology for their systems and consider it a good long-term investment in a changing technology environment.

Caveat - QOS
One caveat in moving to a VoIP telephony solution is to beware of Quality of Service (QoS). Although significantly improved since it was first introduced, the sound of VoIP is not always equal to the voice quality of traditional telephony or TDM.

It may vary significantly during even a brief conversation. Before making a decision to convert to an IP telephone system, it is wise to check out a demo for the system under consideration. Compare the quality of sound to what you are accustomed to hearing.

Cabling for IP
IP systems generally require Category 5 or 6 cabling (just like your data network). Traditional telephony systems require only Category 3 cabling. If you are installing all new cabling anyway, consider using Category 5e throughout your office, even if you are using a traditional phone system. The increased cost of Category 5e cable will likely be a small investment to make for the long-term.

If you are not already installing all new cabling, you may need to include the cost of adding Category 5e cabling to every location needing an IP phone where there isn't already data quality cable available in those locations. Some IP phone systems provide for TDM phones as well as IP phones. In this case, you may be able to use your existing Category 3 cables. Some IP phones can operate on Category 3 cabling, so ask your IP system vendor about cabling requirements.

Summary
In summary, when considering an IP system, evaluate the importance of the IP system features and capabilities for your business along with the investment required (including cabling). Become familiar with the quality of service provided by the IP system under consideration. Ask your vendor for a demo of his proposed IP system so that you can hear how it really sounds.