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Hello all I am making some adjustments inside of our company and trying to save a little bit of money in the process. Here is the scenario we have a full PRI at our head office that is way under used. maybe 4 or 5 channels at any given time. We are in the process of opening two remote offices inside the same city as the home office.

My thoughts were to use an adtran 908e and shoot some of the pri service over an existing site to site vpn. Our head office has a ucm6510 and I was thinking of adding one of the 6204 at each remote site attached to an Adtran 904e.

we want to have individual pbx’s at each office opposed to using one. can anyone think of any reason this wont work ? or have a better idea ? all inbound and outbound calls would be routed out the single PRI.

interested to see if anyone has any better ideas I have never tried to do anything like this with a pri so my knowledge is limited.


I don’t know anything about the Adtran, but I have installations with a UCM6510 in the main office and a UCM62xx in the branch offices. The 6510 connects to each branch 62xx via a VPN connection to the 6510 in head office. I also have each 62xx configured to call each other as well.

There are no problems with doing this as long as each UCM uses it own extension range in my experience.

If you want to save money, I’d swap the T1 with SIP VoIP. I’d also put a SIP account in each branch so that if the main office goes down, each branch can still operate.


I tend to agree with David. The t1 does have an advantage in that it is pretty much immune to any Internet bandwidth issues, but given that you are thinking of using VPNs to distribute the PRI channels; you will have a centralized arrangement in that should there be an issue at the main, it will impact the others and the tunnels in between are dependent on bandwidth.

Using your initial thoughts, you will keep the T1 as is and then establish multiple SIP trunks between the locations and then set the appropriate inbound and outbound routings for the call paths? Will you be using the 90X Adtran as the site routers as well?

I too think it may be beneficial to look at SIP and as David suggested, have each site be independent from the others; yet still peered together for site-to-site calling as well as potential trunk backup. It seems unlikely that if you currently have a full t1 with 23 voice channels and only see such a limited number in use at anyone time, that the other two remote sites would take up the slack.


I agree that buying sip trunks would be the best case for this application but there is no way management will approve that. The current t1 is under contract for 4 more years due to it being bundled with a fiber DIA. I understand the limitations of having a single point of failure but I am just trying to do the best with what I have to work with. I also have configured sip trunks from site to site so they can call each other but I didn’t think it was possible to do that for an outgoing route ?


You can add a separate SIP trunk to each branch’s system to handle outgoing calls. You can also create rules that will allow the branches to be able to make calls out through the main office T1. You use both with the former being a secondary route for outbound calls in case of a failure to/at the main office.


ok I have attempted to do exactly what your describing and I must be missing something. I am attempting to dial from site a OUT through SITE B’s PBX PRI

Configuration is as follows


Outbound Rule Created as Follows

Privilage level set to national.

No digit stripping enabled., have also tried setting stripping to 1 to remove the 2 before it gets sent to site b.



Inbound Rule Created on Sip Trunk


no digit stripping, have also tried with setting the strip digits to 1
default destination is BY DID.

any help here would be really appreciated. I have been able to successfully call extension to extension in each site just fine its only the ability to call outbound through the remote PBX I cannot seem to get working thanks.



See if this video helps


Thank you SO MUCH!. That was exactly what I needed and I was literally doing everything in this video except checking the box for dial trunk. Once that’s checked everything works perfectly fine!.