[cisco-voip] Types of PRIs: "Voice", "Voice, Video and Data", "Unrestricted Digital"

[Robert Kulagowski]

I've got some confusion regarding ordering PRIs from the various 
carriers.  With today's IOS, I can't use a 2851 as a H.323 to H.320 
gateway, but maybe someday I might, if that code ever comes out of beta. 
  What I don't have an answer for is whether or not I need to order a 
different kind of PRI.  As far as I know, a PRI is a PRI, and the B 
channel is just carrying bits, so for now I should be able to take a 
PRI, do some TDM add-drop and allocate channels to a video unit.  But 
I'm getting different terminology from various PSTN phone companies. 
Some are saying, "Oh, that's a different kind of PRI".  Some have no 
clue what I'm talking about.  All of them want $$$ to even think about 
the question.

So, if I'm going to order a PRI that I'd like to use for voice calls 
now, and for voice and video calls later, what do I need to tell the 
phone company?