I have three offices in a state. We call between the three offices a lot. I do not want to replace the PBXs that we have in the offices right now (aka can’t get management to go for it after the money they spent on them). So what I was wanting to look in to was if I could get two T-1 cards in an * box in each of the offices. set them up so that the office PBX T-1 comes out in to the * system and then it routes the calls, that are going to the other offices over voip, but sends all the other calls out to the phone company’s T-1. could or has some one done some kinda of setup like this?
i would probably get an additional T1 card in the PBX (if there’s not already a spare there … and why would there be ??). wouldn’t it be better to have an Asterisk server with a single T1 card linked the to the PBX, then the PBX routes certain calls to Asterisk which then forwards them over the VoIP trunk, then back to the destination Asterisk/PBX via a similar setup at the remote end.
this way you can set it up with disturbing the current setup and users too much, e.g. when you need to restart Asterisk/your box you won’t be taking down the entire PSTN connectivity.
OK I would look at the number of concurrent calls between offices.
In some cases for small one to three calls I have found that I was able to use upto three Iaxy devices and “connecting” the offices that way (using the VoIp lines for interoffice calls)
For larger setup I use the IAX2 trunking / a mix of CF and follow me…console paging between offices… I drop a asterisk server at each end
some older PBX you can just punch down a pigtail with RJ11 on one on the 110 block and program into dailplan of PBX (press 8 not 9 and get VoIP line)
I’m still using Asterisk as a front end to my PBX. We haven’t made the complete move to Asterisk. But, I’m happy with the results I’m getting with this setup. My PRI comes from my provider, into Asterisk (on a dual PRI card), then out to my PBX.
As far as having an additional PRI card in my PBX and then doing the routing that way, I would have no clue how to do that. Every question I asked about routing with my PBX resulted in a “You can’t do that with this system, only the next system up can do that.” Whereas, I CAN do that with Asterisk, and it’s extremely simple.
We were using ISDN BRI lines and analog lines. I got a PRI card for our PBX and had everything setup on Asterisk and ready to go when the PRI was installed. What would have cost me several thousand dollars to have our PBX setup to handle the PRI costs me absolutely nothing.
So, I’m kind of a fan of letting Asterisk handle the routing.
I can also see the benefit though of not affecting the whole system if you need to restart Asterisk. I guess the question becomes, is this a 24/7 operation. Mine is not. I can do what I need to do afterhours and on weekends.