RECOMMENDATIONS Multi-Site PBX solution

[JayG30]

Hello everyone,

Looking for some insight form more experienced people in this area to see if I'm on the right track.

I have an asterisk server at our main facility (call this Site A). It uses SIP trunks and we have ~25 DID's. It has worked very well for us.

We have a second facility (call this Site B) we purchased located a few states over. That facility has an old Toshiba Strata CIX 100 PBX. All the cabling is old telephone cable and 66 blocks. It looks like it is running off a PRI. Service is through Verizon.

Basically, they want to;

1. Allow inbound and outbound customer service calls that come into Site B to be handled from both facilities (probably with some day/night stuff as well). Primary day support will be at Site A with Site B being available if high volume. At night Site A is closed, so Site B is primary. The dial out # would have to appear to come from Site B in this case, as it is a long standing business.
2. Must retain the phone #'s (specifically Site B's lines with Verizon).
3. If possible I'd like this ability to call out as Site A or Site B independent of any connection to the other facility (ie. is it possible to register a SIP Trunk at 2 facilities so both could place calls from that # at the same time (while still retaining things like the pattern in which they ring)? Or would I have to route calls to the other PBX?)
4. This will be more for me to determine when I see the bills, but find ways to reduce cost of telephony at Site B. I'm almost positive they pay a lot more then they would with a per minute SIP provider.
5. Optionally (mostly because I think would be useful), allow extension to extension dialing between facilities.

So, first off, I'm pretty sure this is going to be difficult/impossible to do with the Toshiba PBX remaining. And I think you "could" perhaps make this work with Verizon trunks but I'd have to get a PRI card instead of doing straight SIP.
My initial thought was setup another asterisk based PBX at Site B, setup an IAX connection between it and Site A (or setup a site to site VPN), and move the Verizon PRI's to a /min plan that allows us to handle the flux we see in call volume. Never done this so not sure of some specifics (which trunk go on which PBX, failover abilities, etc) but pretty sure you can do this.
Anyway, I'm not sure how best to handle this type of setup and was hoping to get some guidance.
Thanks.

 

[matthew]

I've never seen or heard of the Toshiba PBX (not really used here in .au). I had a quick look at a data sheet for it and apparently it's capable of SIP trunking. Unknown if it requires additional hardware and licensing. This might save you a bunch of expense if you keep it and do some routing between the systems. Basically, it looks like a programming exercise. Some of your integration desires will be a challenge using two PBXs of any flavour, but with some planning and compromises, you should be able to get close. Some thoughts:

1/ Routing incoming calls is easy. Somehow having the systems intelligently know what outbound number you want to present without intervention is not. You will probably need to have some manual process whereby the staff at Site A dial a particular predigit or some such to choose the outbound CLI (ie, route the call out via Site A or B). Also see my next note.
3/ This will really depend on the provider at each site. Some allow you to number stamp any old number you please, others won't.
5/ If you want any kind of integration between the systems for call handling, this will probably come with the territory.

Good luck. I'm sure others will be interested in how you tackle this, so updates will be welcome.

 

[atsak]

Well, if you were desperate to keep the Toshiba PBX you could setup an Asterisk PBX with a dual T1 gateway. TErminate the T1 from Verizon on the gateway on one port then the other port onto the toshiba; pass the calls from the port inbound to the Asterisk PBX and do interesting things, then pass the calls through to the Toshiba on the other port. But I wouldn't bother with that.

Change to a PIAF system in both places. Solve the wiring issue if needed using either FXS gateways to the 66 block and dumb analog phones or use some of the phone to ethernet converter switches there are around (slow but suitable for VOIP which does not need a fast connection)..

Then yes, an IAX between both systems and an outbound route that specifies the extensions on the other system. You can set your inbound routes to terminate either on the local PBX or on the other one by creating an inbound route that points at the trunk of the other PBX . Then the call arrives at the other PBX for handling.

You can send any caller ID you like out of either PBX (depending on carrier) but you'll have to use a prefix to force that, unless you want all calls to a certain area code to have a certain outbound caller ID.

Anyway, everything you discuss is relatively straightforward to do.

 

[JayG30]

Thanks for the replies.
Yea, I really am not a fan of this Toshiba unit (and neither is Site B). The problem is that it was never programmed correctly. I had a system a bit like this in the past from ESI. They don't give you any ability to do simple tasks (add, move, change, voicemail, etc) let alone more complex things (IVR, ring groups, CO lines). You end up having to pay someone that is authorized to do everything to the tune of $100+ an hour or just deal with it. Having an Asterisk based system has been so freeing. Long story short, I don't see the Toshiba surviving this process.

I looked at this a bit more and after some reading now realize that you can use PBX's from different manufacturers and still set this up. It seems like there are ways you can do it even using TDM (instead of IP). But having two systems that support SIP (or better IAX) makes it easier. I imagine having two systems that are the same though would make this a lot easier.

So where I'm at now is 1 of 2 approaches.

1. Setup Site-to-Site VPN (OpenVPN) and just have the remote Site B as part of the main Site A PBX. Basically treat Site B as if it is using a hosted PBX service (except Site A will be doing the hosting). Port the #'s over to a SIP Trunking provider and set that up on the main PBX. Setup so that certain area codes dial out as certain #'s by default (perhaps least cost routing?) and setup a prefix that they can append to force dialing out a certain trunk.
   • Advantage is consolidation of hardware and trunks. Everything is in one interface and you really can't get a better "integration" this way as it is all just 1 system.
   • Disadvantages are that Site B is reliant on internet and VPN connection for any form of calling. This could be an issue.
2. Setup Asterisk based PBX at Site B, use IAX to connect the two. There are plenty of instructions on how to do this online.
   1. Advantage is Site B can remain online if IAX connection to Site A goes out. If internet goes out (and we port to SIP Trunking) they would at least still have internal calling.
   2. Disadvantage is that you now manage two systems. I've read and it seems that if you setup unique extension ranges on each PBX you can do extension dialing without prefixing. If you don't you have to use prefixing. You have to manage separate systems. Extensions from one aren't visible in the other. You can't really do a unified directory (mine queries from Samba4 LDAP). I also imagine that someone at Site A can't just take their phone to Site B (or log in if using hot desking) because each PBX would have it's own distinct set of extensions (although perhaps this could be handled through a VPN allowing the phone to reach the PBX at Site A).

The other thing I saw mentioned but haven't been able to find much detail on the advantages it might have is DUNDI. Not sure how/if that plays into this.

Ideally I'd love to have two systems at both sites so that they could operate standalone, but instead of them being "islands" they would be mirrors of each other. Think Active Directory multi-master type systems or real time DB replication. However I don't think that is possible, especially over a WAN link.

 

[atsak]

Dundi is overkill for a two system setup. Just trunk them and use unique extensions. You can replicate to both sites using Hyper V 2012 R2 (free though not open source) if you desire that setup. I do it that way. Failover works if you set static MAC addresses on the guest OS, though you have to deal with the IP address change post failover (but that takes 5 minutes) between sites.

Setup 2 is how I do it, over VPN between the sites.

 

[JayG30]

Thanks atsak. I like to go with the flow and do things like others. Usually turns out better that way. lol
I completely forgot I could replicate the Hyper-V VM offsite! And turns out I just started upgrading Site B to Hyper-V Server 2012R2.

Also, I found this page to be very helpful for the visuals of the different multi-site setups.
https://askozia.com/voip/connect-multiple-pbxs-and-ip-phone-systems/