Centralized 3CX server and several branch offices

[jjwerkman]

Does anyone have experience with this sort of configuration? Does anyone know or there is i.e. a case study or guideline with some steps about do's and don'ts? Thanks.

 

[mixig]

Hi,

one 3cx server on central side, or on each branch office additional 3cx server? I have few setups with one centralized 3cx server and all other offices are connected via VPN to central site (voice problem if remote offices are having bad internet connection, disconnect call.. i.e.) but it`s working well. With additional 3cx servers you can setup 3cx bridges:
http://www.3cx.com/docs/connecting-offices-bridges/

 

[jpillow]

You have a few options,depending on your particular needs you will have to decide which best fits your organizations needs.

1) you can use 3cx Bridge and make the central office master IP PBX, and remote offices slave IP PBX's and send calls across the WAN. the biggest drawback would be that you will have to purchase a license for every locations

2) you can place PBX at Central location and place extensions at remote site either using SIP Proxy manager though you will need to have a machine at the remote location with SIP Proxy manager always running. Or just use remote extension without sip proxy manger using STUN

3)Set up a VPN between all locations ave all handsets appear to be on the same LAN.


http://www.3cx.com/blog/docs/provisioni ... extension/

http://www.3cx.com/docs/connecting-offices-bridges/

 

[jjwerkman]

Thanks for the reply's!

 

[netswork]

I am about to do an install for a customer with 5 sites connected via MPLS T'1s. For redundancy we are installing a 3cx system at each location with their own PSTN gateway.

All of the systems will be bridged together. Only thing you need to worry about is extension management so that each system has their own extension range separate from the others.

We offered to do a consolidated install with only one 3cx system for all locations but they liked the extra redundancy in having a system at each location. That way if the main site goes down the remote sites still function.

 

[sigma1]

We should have a case study out shortly (it has been in the works for over a year). It is perfectly do-able without the complications posted by others. Multiple systems will reduce the effectiveness of certain features such as SP etc. We install mostly large to very large 3CX systems in complex infrastructures, feel free to reach out to me directly with questions on this subject.

 

[netswork]

How do you handle situations at the branch level if there is a break in communications between the branch and the main site with the PBX?

 

[jjwerkman]

@netswork, when the communication is broken, the number can be directed to a cell phone. Our line is very stable. We have more power outage than problems with our fiber line.

 

[3CXfoxhallsolutions]

There are huge advantages in running all offices through a central pool of SIP Trunks of course, as you can then cut trunk costs massively and control everything centrally off a single resilient 3CX server and license. Things we have learned to look out for however ...

1) You'll need to configure Outgoing parameters carefully so that different branch offices are identifying themselves with the correct Caller ID on outgoing calls. Check out how your SIP Carrier handles Caller ID (we request a setting called CLI_PASSTHRU from our carriers) and then 3CX can be configured to input CLI on a per extension basis. So - research pooled SIP trunks and outgoing CLI ...

2) All of your branch sites will be running remote extensions, and this can be done direct via Internet, or via the 3CX Proxy Manager running on a server or PC at the branch site ... It's probably this bit that will take the most 'playing with' just to confirm the most stable way to do it (as it can depend on things like your choice of router, phone & ISP). Lot of work here that can only really be done by reading the 3CX how-to's and setting up trials. Don't leave this bit to theory!!!

3) Internet will be the glue that ties the whole lot together - so your 'central' site actually needs to be the place that has best access to Internet (which may not necessarily be the head-office, or even the place with the most handsets!). Choice of an ISP who can a) get you the bandwidth, and b) get you the business level SLA is critical here. This is the most important bit - as bad choice here will make the whole thing crash and you'll have to unwind everything back to as it is now to get your company telecom's back on track. Just bear in mind that you'll need (!worst case!) about 120kbps bandwidth for each active call, and that will indicate your Internet needs.

4) Your own network is going to be damned important too - in regard to if you are running phones & PC's together? or putting them on V-LAN's or separating things completely. You'll need to school up on network Quality of Service (QoS) issues. You may also consider (if you have a high-speed DSL), allocating some existing bandwidth in a 'shared' Internet connection that's going to support voice & data. Again you'll need to school-up on using routers and smart-switches to give your voice network reliable QoS.

Once you have the above worked through, running a centralised 3CX is pretty straight forward, as the number and locations of the remote phones don't really effect things much. Your model can be applied to any number of phones at any number of branch offices ...

If all that looks complicated - you can understand why while there is a high degree of 'Do it Yourself' potential in 3CX, you can get a lot of value in getting a 3CX Certified partner involved who has done all this before. It's going to cost a whole lot less than getting it wrong ... best of luck in your project ....

 

[netswork]

There are huge advantages in running all offices through a central pool of SIP Trunks of course, as you can then cut trunk costs massively and control everything centrally off a single resilient 3CX server and license. Things we have learned to look out for however ...

2) All of your branch sites will be running remote extensions, and this can be done direct via Internet, or via the 3CX Proxy Manager running on a server or PC at the branch site ... It's probably this bit that will take the most 'playing with' just to confirm the most stable way to do it (as it can depend on things like your choice of router, phone & ISP). Lot of work here that can only really be done by reading the 3CX how-to's and setting up trials. Don't leave this bit to theory!!!

3) Internet will be the glue that ties the whole lot together - so your 'central' site actually needs to be the place that has best access to Internet (which may not necessarily be the head-office, or even the place with the most handsets!). Choice of an ISP who can a) get you the bandwidth, and b) get you the business level SLA is critical here. This is the most important bit - as bad choice here will make the whole thing crash and you'll have to unwind everything back to as it is now to get your company telecom's back on track. Just bear in mind that you'll need (!worst case!) about 120kbps bandwidth for each active call, and that will indicate your Internet needs.
.

While I agree with what your saying, if I was going to do an install with multiple branches that were not connected via a private network I would connect the sites via VPN so that you do not have to worry with remote extensions and NAT issues.

The customer I am working with prefers to have a pbx at each site and then use bridges because if the "main site" goes down (internet/WAN/PBX) they don't want all of their locations to be out of service. Having a PBX at each location is more expensive...but still cheaper than a Cisco unified communications solution with presence.

90% of all of my installs have been with PSTN connections, generally PRI's because the customers will not accept any voice quality issues or outages.

My company personally uses nexvortex sip trunking but we have 50mb fiber to the internet. Nexvortex has been solid but they still occasionally have brief outages...usually only for a few minutes. Generally the customers we are targeting would not accept that type of outage and choose to go with PSTN connections. The cost savings in VOIP is not justified to them if they have an outage or voice quality issues.

Around here AT&T offers a product called IPflex. Which is a digital internet circuit delivered over fiber or T1's and they layer voice on top almost for free. The customer has to have internet anyway and to add voice is only like $17/month per call path.

 

[jpillow]

I have clients that choose both VoIP and PSTN gateways about equally, while I personally prefer SIP trunks in most occastions the only one I can think of is not is if cable broadband isnt available. I've never really had any QoS issues as we usually sell router, switch, pbx, pretty much the entire network same equipment and assure we have more than enough bandwidth to do so. If you can get Cbeyond in your area and have T1 needs and what to use SIP trunks this is hands down the best route. They are the only CLEC in know of even tested on 3cx I just signed up a client for 6x6 circuit with 8 sip trunks for about $399 dollars. Which is great pricing by any stretch of the imagination anywhere. I'd have agree and say either use private VPN or SIP proxy manager that will eliviate alot of QoS and NAT problems. The majority of my clients either have multiple locations or remote workers and we've discovered many different ways to connect them to the network and more importantly what not to do. Really at the end of the day it wil be trial and error to determine what will be the best for your client. Good Luck and please update after implimentatio I'd like to know what you did and how it worked out for you.

 

[paul.hadley]

I have set up multiple 3cx servers and linked them together without any problems.

I didn't want to rely on one central server so I followed this plan.

Set up each PBX at each location in the normal way with your relevant lines, extensions and ring groups etc.

Ensure that each PBX uses a distinctive range of extension numbers, for example

PBX (1) 100 - 119

PBX (2) 120 - 139

PBX (3) 140 - 159

PBX (4) 160 - 179

Then on each PBX add extra extensions for each PBX on the system, for example

PBX (1) 802 - 803 - 804

PBX (2) 811 - 813 - 814

PBX (3) 821 - 822 - 824

PBX (4) 831 - 832 - 833

Do not put any description into the "Last Name" "Fist Name" fields as will effect the caller ID function and ensure that each one can be registered to from outside the Lan

Now on PBX (1) set up a voip provider as "Generic Sip Trunk" with the external IP of PBX (2) External number of 811 and what ever password you set extension 811 on PBX (2) to. Add a dial rule for the trunk for numbers that start with 12 or 13.

Repeat this again on PBX (1) for a link to PBX (3) with an external number of 821 and a dial plan for numbers that start with 14 or 15 and PBX (4) with with an external number of 831 and a dial plan for numbers that start with 16 or 17

This needs to be repeated on each PBX to provide a Sip Trunk from each PBX to each PBX

The end result should be that any user, on any PBX can call any user on any PBX direct from one PBX to another without relying on a central PBX. This improves redundancy and also reduces bandwidth and latency as each call is made as efficiently as possible across the Internet without having to be relayed through another connection. Also as each trunk does not require a constant registration it reduces call failure due to temporary loss of registration.

So for example user 100 calls user 120

100 dials 120, the dial rule puts it to "Generic Sip Trunk (2)" which forwards to extension (811) which calls extension 120 and the call completes.

Or user 100 calls user 120

100 dials 140, the dial rule puts it to "Generic Sip Trunk (3)" which forwards to extension (821) which calls extension 120 and the call completes.

The only disadvantage to this is you are unable to share presence information across the PBX as you can with a 3CX bridge. And the caller ID on extension 120 will show the correct description for extension 100 but the number as (811). To make this clearer to the end user I usually set the extension ID as for example "(100) PH Office"

Its a little more tedious to set up than a 3CX Bridge but it does reduce the load and possible failure implications on a central server.