ISDN and Video Conferencing

The user only wants to use the device on one end, as the remote video conference unit only has the option of ISDN through their carrier, or they just do not want to change. I will have to look into these devices, but they can be used on one end to convert the ISDN to work over a T1 or PRI? I guess my confusion is that the ISDN uses a number to initiate the conference, and how would that work over PRI. I guess this would have to be a voice PRI. Sorry for my ignorance, and thanks again for the help!

ISDN communicates using the Public Switched Telephone Network (PSTN).  The PRI/T1 also uses the PSTN to communicate.  What the gateway does is accept the PRI/T1 circuit and then allow the LAN to communicate to the gateway to send the call to the PSTN.  Both the gateway and the ISDN will utilize the PSTN to make and receive calls.  Don't apologize, this is how we learn.

So basically I am getting the gateway which will accept the channels for the PRI from the carrier, and I will break X amount of channels off for voice to the phone system, and X amount channels off for the ISDN interface into the Conference Unit. Now, if this is a voice circuit, then how does the system use the channels for Data? Is this unit basically serving as a CSU/DSU?

Now it's a little different with a Phone switch involved.  If you are planning to allocate voice circuits and a portion to data, then you will need to do this a tad differently. The PRI gateway device uses the circuit as a conferencing circuit with DID bound to the PRI.  If you want to utilize this for inbound calling to your Voice PBX, then you will need to have a phone switch that is H.323 capable or SIP capable.  Then what you would do is forward the DIDs bound to sets to the phone switch and the DIDs destined to video to the Camera.  Make sense?  The Gateways have an internal CSU/DSU but the main function is to serve up calls to H.323 endpoints registered to a gatekeeper.  If you already have a phone switch in place, you may be able to use it (depending on the make/model/options) for what you want to do here.  Do your ISDN lines come into the phone switch now or do they go to a MUX attached to the video camera?

I am still a bit confused. Yes, the isdn is directly connected from the wall to the unit. there are 3 (i think) ISDN lines going into the unit so they can do 384K connections. So your saying it needs to be a Data pri, not a voice pri. I dont think this will work, becuase we have to provide the phone system with PRI channels set to NI2. The system does not support h.323 or sip trunking. However, if it is a data PRI, then im thinking we could only provide IP to the conferencing unit, there is no way to point a DID over a data channel, right?

No, you do not need a data PRI, if you did it would be called a T1 circuit as they are essentially the same thing only one is defined for voice (PRI) an the other is defined for data (T1).  If you wish to route calls to both a PBX and a Video endpont, you need a device that can deliver either or to your different endpoints.  With that said, you should probably provide the PRI from the Phone switch to the video unit. Without knowing what your PBX is, it is hard to determine if you can do that.  You could go to the PRI gateway, but you will need to have a PBX that would support call signalling and setup from the gateway either over SIP or H.323.  If you decided to go through the PBX, your PBX would need to have the ability to mux multiple channels together for the video calls.  

What Videoconferencing system does your customer use? Most VC systems support IP aswell as ISDN. Wouldnt it be far cheaper, reliable and faster to use an IP connection instead of fudging around with ISDN?

They conference with a Corporate office in Europe, and ISDN is the only option on that end. I agree IP is easier and more efficient, but its not an option unfortunately.