TDMoIP

Our tech world is full of acronyms. The title of this post is an acronym that you may already be familiar with. Depending on your telecommunications infrastructure and future plans, you may want to become familiar with it if you are not already.

TDMoIP stands for time-division multiplexing over IP. I don't want to cross everyone's eyes with a detailed description of time-division multiplexing. Let's be honest - I'd be regurgitating something I've read anyway. Suffice to say that TDM is how your phone conversations are carried over the public switched telephone network (PSTN). Voice traffic is transferred to channels and passed across the PSTN and the same concept is used to take voice traffic on some school district networks and pass it across some channels of a T1 telephone circuit (or something similar). Configuring hardware for TDM networks (think CSU/DSUs and the like) always involved settings for the type of encoding, clocking and presetting certain channels of the circuit for the type of communication desired.

Fast-forward to today, where many schools districts have installed fiber-optic high-speed connections for their networks. These faster links replaced those legacy T1 (or 56K?) data circuits and we were passing data between sites at faster rates than ever before. That's great for data, but what about the voice traffic and those channels on the T1s?

Some simply left the T1 infrastructure in place to handle voice traffic. Some were convinced that voice over IP (VoIP) was the way to go and may have replaced handsets and phone system components with a system that truly handled IP connectivihttp://www.blogger.com/img/blank.gifty end-to-end. The problem with some of our districts is that huge investments were made in the original phone systems and the price and feature sets of a VoIP system are beyond the budgets and desires of the school district. However, paying for a data infrastructure as well as the existing T1-based voice pipeline isn't an acceptable option either. This is where TDMoIP may be the answer.

As you may know or could certainly guess, there is technology available that allows you to continue to utilize a 'legacy' phone system (which uses TDM technology) to transmit voice traffic over an IP-based network. I'll link one category of products made by RADirect. I think there are other companies that make this type of product, but I've seen a few districts use this company's product in the past. Voice traffic and data traffic are completely different and have different requirements for quality of service, timing of the traffic, keeping packets synchronized, etc. If part of a web page doesn't load, that packet gets sent again. If it doesn't arrive in exact order, the end result still looks the same and the page gets rendered very quickly regardless. If you miss packets of a voice conversation or traffic isn't received in an orderly and timely fashion, calls are lost or garbled. I won't belabor the point and will assume that you have some idea why this sort of equipment is needed.

The amount and type of gear you need will vary based on many local factors, but I wanted to take a minute to point out that this can be done and is being done to extend the life of your existing PBX-based phone system and take full advantage of your high-speed data network without dealing with the redundancy of an additional infrastructure left in place for only voice traffic. Take care.
[Image: Library of Congress]