Remote office architecture strategy

Please provide your thoughts, we are divided about this subject.

We have several clients that are hosted PBX subscribers today and we will be migrating them to FreePBX. Our customer base tends to be professional service firms that often have multiple offices. A typical customer might look like this:

  • headquarters office with 10 people and solid cable or fiber internet
  • remote office with 3 people and solid cable or fiber internet

We are stuck on the best architecture for a FreePBX solution. One “camp” thinks we should install a single FreePBX box at HQ and have the remote office connect through VoiceVPN (we use edgewater fireware/routes that support VoiceVPN) to the HQ FreePBX server. The other “camp” thinks we should install a FreePBX server at each location and “tie the two together” with outbound routes.

Our internet here in Central Florida is quite good with minimal service issues (I did not say zero issues, just minimal).

As we see it, the main benefit to a single FreePBX box is less setup, administration, integration, and failure points. The drawback is that if the main office internet goes down, the remote office cannot call 911. We believe (any comments here) that voice quality through the VoiceVPN will be fine (again, our interent providers are quite good, but not perfect).

To date we only have installed single offices. We are starting to install these multiple location customers and want to provide the best solution, but are torn between these 2 philosophies.

Appreciate your real world experiences and general thoughts on this subject.

You need to consider 911. If you have a single server at the central location that has your voice trunks when someone at one of the remote offices dials 911 the 911 response center will see the address of the central location.

If you trunk provider will allow you to have different addresses depending on the out pulsed caller ID info than you can make this work.

Yes, we can flash a different DID depending on the office making the call, so the address given to 911 will be correct.

911 concerns really stem from if the HQ goes down, the remote office cannot dial 911 because their phones are down when HQ is down.

I understand that you can send have the remote office use a specific phone number when they make an outbound call. The question is if your trunk provider will allow you to have the physical trunks terminated to your central location and allow you to specify different physical postal addresses for different numbers.

Ok, reading through this, I gather HQ has PSTN connectivity that Remote users use as well, upto and including 911. I’d recommend 2 independent systems. HQ vs remote. And setup a SIP Trunk between the two locations. Remote Office can use HQ for/as primary route for PSTN and 911. Setup a backup SIP trunk on the Remote FreePBX to your PSTN provider (for LD and 911 as well). I noticed FreePBX “monitors” the SIP Trunks to peers for up/down status (maybe using SIP Options???). Should the trunk to HQ fail, the Remote Office will have it’s own route to the PSTN and 911.


Quick recap:

HQ has sip trunks. HQ flashes their DID outbound for e911 and remote will flash their DID outbound for e911 - so only 911 concern is that if hq goes down, no telephone service at remote. Given reliable Internet, is this really an issue? After all hq (who has 15 employees) is down, is remote with only 3 employees really an issue?

With sip trunks at hq, if we voicevpn remote to hq and initiate all sip calls from hq, is that a sound or unsound strategy? Internet is good, ping time through the VPN are low.

If the “best” strategy is 2 freepbx boxes, why? Not just, “it’s better”, but why is it better? Will fop integrate between offices? Can you call park in hq and pickup in remote? Can you intercom between offices? How much extra work will it be when a new employee starts and we have to change the dial plan routes between offices? What reason am I giving customer to pay more for two boxes versus one?

Thanks for your thoughts and “lessons learned”.

You did not mention what kind of phones you are using. Most SIP phones have an emerency proxy service. I would put an SPA3102 and a lifeline POTS at each location and set the SPA’s to accept calls without registration.

Central server with VPN is the way to go if bandwidth, jitter and availabilty meet the service expectations of the customer. The customer expectations should dictate the technical design.