atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's BRI to PRI? Polycom Video Conferencing

I have a customer that is getting a PRI dropped in house. They also have x3 BRI for their polycom video conferencing.

They posed an interesting question to me today and I think it can be done but I need to get some more background information on BRI (never seen much of it here in north-america).

Does a BRI basically work in the same manner as a PRI but just as 2B+D? Or is the signalling different? Also, when the BRI bond's two channels is this something that is done on call set-up over the D-Channel or something that is done at the line build out?

What the customer has is a Full PRI being brought in house, and I am researching if it is possible to have Asterisk use a BRI card to send the polycom video conferencing over the PRI instead of having seperate ISDN lines. The biggest thing that will determine wether or not I can do this is just how close BRI and PRI operate, and what kind of BRI line the polycom needs. If i'm lucky then hopefully the polycom dials each B-Channel to the other end and doesn't need anything special. It would be nice if the polycom took care of bonding the BRI's in it's own box instead of needing a special LBO from the switch.

Any input is much appreciated. Thanks...

BRIs do function exactly the same as PRI's, but they don't offer as much flexibility. For example, a PRI can have hundreds of DID numbers pointed at it, while BRI's generally only allow one number per B channel. Not a big deal for video.

The other thing that BRIs offer is the various termination options. You can have a "U" termination, where everything rides on one pair, or the "S/T" termination which is two pair. Most people go with the "U" version these days.

As for bonding, that's all determined by the serving CO and the terminal equipment. I don't think that you can use the D channels from subsequent circuits as B channels if that's what you were thinking. You can bond multiple circuits together, but it's still going to be two B channels per circuit plus a serving D. The subsequent D channels are just wasted bandwidth.

Well, in that case, now it's just a matter of figuring out what my BRI options are for this Polycom thing. First I need to figure out which model tho

Few years ago we setup something similar. Forget the model, but there was an adtran unit we installed ahead of the phone system, that basically "split" the PRI. It provided a port for the phone system and the video conf.

Hmmm, you don't happen to remember a model # do you?

I'm not 100% sure how well Asterisk, or even if it can, route the BRI. If I have a reasonably priced piece in front I would prefer to go that route.

I'm curious as well. I'm sure that there are others made by Adtran, but the only Adtran device that I can think of is the ISU 512. It can bond up to 4 BRIs. As far as splitting a PRI, I'm also interested in how this would work. It seems that it could work, if the calls to the VTC were routed to the PRI, then split off by the Adtran, and sent to and from the video conference system.

Most video conferencing systems that I'm familiar with require inputting the individual SPIDS from the BRIs during the initial setup. Using three BRIs for Video Teleconference (Polycom, Tandberg, Sony, etc.) is pretty much standard where I work. There are a few that use only one or two BRIs, but the video quality is below marginal (choppy, like a news broadcast over a very low bandwidth satelite link). The combined 384kb of bandwidth from the 3 BRIs provide for quality video conferencing.

It has been awhile, but a quick look at adtran.com it may have been the Atlas 550. You can call them and they will help you. very helpful folks.

Like Ed said the Bri and Pri are basically the same, the bri has only 2 channels and the d channel is just for operational data for the system, but I have heard that the German bri can use the d channel for credit card traffic.

You can have more than 2 numbers on bri if you pay extra per 10 ddi/did numbers, I have 50 numbers coming in on 3 bri, but has to be on a system to be any use.

You could put a pri card in the poly com unit and use as required or have the pri on a telephone system with 3 bri extensions to the poly com. the poly com should set up the multi channel link as it does on the 3 bri, just add 9 in front of number.
For incoming calls you would have to point 3 ddi/did to the 3 bri extensions for the unit to set up the call. You may be able to put in to 1 hunt group but I don’t know if it will work, as far as I know you have a number per bri to set up correctly