New PBX Install Advice Needed, 150 users at 20 sites

Hello PBX Experts,

I own and operate a small IT firm in the Southern California area. We provide managed IT services, hosting services, and we service VoIP systems…when we need to. I’ve always had an itch to deploy a FreePBX system, and now I may finally have an opportunity. Please excuse my lack of knowledge in the PBX arena as I continue this post…

There’s a company that we provide managed IT services for that is about 150 users across 20 sites. Their headquarters has a ShoreTel system with a PRI, and their remote sites have various analog and digital systems, with 2-8 separate analog phone lines/numbers each. For internet, each site has 3 mbps, with the exception of a few with 2mbps and one with 10mbps.

I would like to streamline their phone system, and cut back on unnecessary costs. I feel like this is our opportunity to get our feet wet with FreePBX, but I wanted to reach out to you, the community, for advice before we do.

My plan is host their FreePBX server at our data center, which has neck breaking speeds. My concern is whether or not its a good idea, considering their not-so-neck-breaking speeds at their locations. Here is a comprehensive breakdown of my questions/concerns:

  1. Is 2-3mbps sufficient for a handful of concurrent calls? Worst case, we could upgrade bandwidth, though that’s not cheap for most of their locations
  2. Could we keep the main number(s) for each site and port them over to a SIP trunk? OR, how would we go about keeping those main numbers?
  3. Phones: can anyone give us suggestions on reliable/cost-effective phones? Pre-owned is fine.
  4. What costs would we be incurring to run a system like this?
    (a) Rough DID costs? (or whatever we would need for the phone numbers and service themselves)
    (b) FreePBX license costs for commercial modules, if any would be need?
    © Other costs I’m not thinking of?

You advice and knowledge and time is greatly appreciated. Thanks all.

Direct answers to your questions:-

  1. no problem as g711 calls take about 80Kbs each, BUT you will need QOS effectively deployed to make sure that RTP traffic (audio) gets priority over standard network traffic.

  2. Yes, if you look at your extant bill you have been paying a few dollars a month for “number portability” on each of those numbers (CA PUC mandate) and those charges will go away :wink:

  3. That will cause all sorts of fanboyz responses, I find Aastra and Polycom excellent.

  4. DID’s are about a dollar or so a month each if you choose the right sized VSP. The commercial modules provide extra functionality, but many have no need of them for a fully operational PBX. Other costs are the cost per call, look for per minute pricing, it almost always works out cheaper, expect between 0.005 and 0.02 per minute for NANP calls depending on usage and also be mindful that you will pay for both inbound AND outbound calls at that rate, unlike the traditional PSTN providers where the inbound calls are subsidized by the monthly trunk costs (1MB’s in CA are still +20 dollars each and a zone 3 call is +30 cents a minute).

Other things to consider is that traditionally your customers expect “5 nines” availability, that’s about three minutes a year of “not working” so consider a true SIP proxy cluster in front of your FreePBI’s and each FreePBX should be redundant by the old fashioned DRBD/corosync method or IMHO full virtualization of the machines in VM’s I suggest Proxmox which as an IT managed service provider you will understand instantly it’s benefits , two machines are scary use two big ones for the grunt work and and a smaller “quorum” machine to save your hair when everything goes belly-up. On that note look into a proper BGP implementation as one bad route will spoil all 150 users. VSP’s are also of varying quality you need one that can failover bad routes to your other proxy members if your bgp and redundancy fails at the worst possible time.

Well structured SIP services are always better and cheaper than PRI’s (ask ATT, they only want to sell you PRI’s over a very limited SIP service now, go figure that one out :wink: )

There are other wrinkles like faxing if important but solvable, bear in mind FreePBX is a very good PBX but very bad multi-tenant solution .

Your use case looks reasonable.

Hi dicko, thanks for the quick response. Would you mind clarifying a few things? Again, this is all a bit new to us. So…in direct response to your direct responses:

  1. Great to know the bandwidth requirements. QoS will be no problem. Good to know that we simply need to give RTP priority. Thanks for that.

  2. Good to know as well.

  3. Great, we will shop around.

  4. I was unaware of call costs. So, at $0.005 x 8 hours x 60 minutes x 30 days x 5 concurrent calls at any given minute would be $360 per month, plus the $1 per DID? Would we only need 1 DID per site? Meaning, on that single number (aka DID right?), a pool of phones at a certain location for example would be able to receive and make calls at the same time?

Can you briefly explain what a VSP is?

Can you go into more detail about the SIP proxy cluster? If it means anything, our data center has ridiculous redundancy as it is, BGP being in place, and new routes being calculated every 45 seconds. We will definitely virtualize the servers.

On virtualization, do we really need a HA FreePBX setup, as our virtualization cluster is HA as it is? Is there any special hardware that would be required? Or simply a dedicated NIC?

Thanks again very much for your knowledge on the subject.

You will need DID’s to match your needs, one DID fo each entity to are trying to reach for example site 1 has a number for the boss and another for accounting . . . . . Look at the whole organization, what telephone numbers do people call in on ?

A VSP is a VOIPServiceProvider

If you have a Proxy, then any call that arrives at the proxy (hopefully a cluster, and in your case with BGP , then the IP that resolves to, will be accepted and handled by any active server within that namespace. (google Kamailio)

If you have virtualization properly in place and a decent fencing system, then when a server disappears an exact copy of the same machine will appear within seconds at the same IP space. It is IMHO much better than the old HA asterisk solution as it scales to MANY machines and a broken two state redundancy will often cause a split-brain that needs manual intervention.

Corosync can handle the the “floating” external IP, just make sure you setup the “internal network” to enable individual management of the redundant machines, I personally use glusterfs as the backing storage for all those machines, some prefer iscsi or fibrechannel and whatever fs underneath it, you can happily use such a network also for access to the dormant instances.

Great, thank you again for you knowledge on the subject.

As for phone numbers, each site has their primary number, which we’d like to keep. On top of that, I see what you’re saying, as we should have multiple DID’s for some sites (dedicated numbers for accounting and other important departments).

I will checkout Kamailio and Corosync. Thank you again.

Generally use 20 days a month and 8 hours a day for commercial usage, and multiply by your Erlang needs (that’s another google :slight_smile: ) but it would generally be between 0.1 and 0.2 of your 150 users, think of that as the amount of time any random user might be on the phone (intra-extension calls would not count against that factor), if an efficient call center that maybe as much as 0.8