TDM(time division multiplexing) is the term used to describe most modern digital telephone systems. These phones work on the idea that you have a dedicated wire from the telephone jack directly to the telephone system’s key service unit (KSU). This method is very reliable and has been the standard for years. With the emergence of VoIP technology these standards are being challenged. I will attempt to explain the differences and list a few pros and cons.
When using a pure VoIP telephone system, your handsets are no longer directly wired to your phone system. These phones are connected to your data network and use the same cable, jacks and switches that your PC’s are using. The voice conversations are being compressed and converted to data packets and being broadcast across your networking in a similar way that all data on your network is being transmitted. The telephone system is connected to the same network switches that your PC’s and now VoIP phones are using. A few advantages to this would be only needing one type of cable in your office, the extension number of your phone stays with your phone no matter where you move it, and in most cases that same phone could be moved to a remote location, such as your home, and used that same way it would be used as if it were in the office.
A few disadvantages to this would be if your data network were to go down for some reason, maybe a switch goes out, you would not only loose your PC’s network but your phones would no longer work either. Think of it as putting all your eggs in one basket. Voice quality is also something to consider, although the technology is getting better, the quality of a TDM phone call is better. VoIP phone on average are more costly also.
TDM phone systems operate by having a dedicated pair, or pairs of wire that go from the jack directly to the phone system. The phone system will normally have different cards in it to support different functions. You will typically have station cards to support your handsets and trunk cards to support your connections to the telephone company. Advantages to this include separating your voice from your data so if you were to loose one you would still have the other. The TDM handsets will typical provide you with easier functionality for preforming tasks such as transferring calls and placing callers on hold, setting up conference calls etc. Sound quality is better on these types of phones also.
Typically TDM phone systems are less costly. A few negatives would be needing a dedicated cable for each phone, if you move your phone (in most cases) your extension number doesn’t follow you unless you make a change in the programming or physically move the jumper to the new jack. They cannot be used as a remote phone.
Emergent, formerly Telecommunication Professionals, Inc., has been serving the Orlando – Central Florida region since 1988. Emergent is a network services, business telephone and data communications company that specializes in technology solutions that give clients a competitive advantage and increased profitability. The company implements technology plans by providing products that fit the client’s needs. Emergent’s mission is to provide cost justification and investment protection.
