I use a PBX with a Sangoma card, specifically the A500. Below is the link for the product
http://www.sangoma.com/products/a500-2-24-port-scalable-st-bri/
On the link you have a demo, which breaks down the components and explains them nicely. One things it also shows (specifically on step 3), is that the BRI module can be inserted either way, however one way is for TE and the other for NT.
I understand that TE stands for Termination equipment and that NT stands for Network Termination. But cannot seem to find any decent information that actually tells me what each of these mean and the difference between them. Could someone point me to a site or resource with this info, or explain it simply for me if you know the answer.