How many SCs do I need?

[MaxDaemon]

Howdy, and Happy New Year!

I've done quite a bit of searching and can't find any kind of rule of thumb that tells me how many SC I should need on the basis of how many users I have.

So, as a for instance, suppose I have 50 users. Obviously I don't need 50 SC for those users.
I'd think I could cover 50 average users with maybe 8SC? Maybe even 4SC depending on their kind of business?

I'm also not finding any kind of report that tells me the maximum number of simultaneous incoming/outgoing calls I'm getting.
Is there a report for that and I'm just missing it?

Thanks for any help you can give!

 

[VoIPTools]

You have to be very careful when you try to come up with a "rule-of-thumb" for estimating the number of simultaneous calls you need. It depends greatly on the organization and how the phone system will be used. Perhaps a couple of examples will illustrate the challenge.

Warehouse/Manufacturer Example.

In a warehouse or manufacturing facility you may have a large number of employees. Maybe some of the staff share a common phone in the warehouse and rarely use the phone. The ratio of simultaneous calls to employees might be one simultaneous call for every 5 employees.

Call Center Example

A call center where staff are on the phone all day with multiple people waiting in the queue is very different. In addition, perhaps this company regularly has large internal / external conference calls. Perhaps phone calls are commonly forwarded to staff in the field. In this case the ratio could be as high as five simultaneous calls per employee.

You have to consider that people waiting in a queue, or placed on hold, or participating in a conference call, are simultaneous calls. There are even cases where a phone call can count as two simultaneous calls. For example, if an inbound call is forwarded to a mobile phone, that's two simultaneous calls -- one for the inbound call, and one for the outbound call. Finally, even internal extension-to-extension calls are counted as one simultaneous call.

Maybe you could come up with multiple rules of thumb based on the company type? I think taking the time to really investigate how the phone system will be used is the only approach.

Simultaneous Call Report

As far as I know there is not currently a max simultaneous call report available from 3CX? There has been talk of 3CX providing this report, but I don't think it has been released. Maybe something will come with the proposed new reporting platform planned for V20 update 5? If you need it, we can provide an approximate number. With the CDR feature you can get a list of every call that takes place in the phone system. The CDR has a start and end date. Then it is a function of identifying where the calls overlap. We can provide this report, but honestly it does not take into account all the edge cases where some calls count and some do not. It would be an approximate count that you could use as a useful approximate.

 

[MaxDaemon]

That's an excellent document.

Right now, the system that will likely move to 3CX has 106 "lines" and something over 1200 users. Max trunk capacity reached in the past 30 days has been 65%.
I don't intend to run the 3CX with that many users per server, so probably using an SC32 license for every server/300 users should be fairly safe.
Thanks for helping gel that in my mind. Do you see anything wrong with my rationale?

 

[CentrexJ]

That's an excellent document.

Right now, the system that will likely move to 3CX has 106 "lines" and something over 1200 users. Max trunk capacity reached in the past 30 days has been 65%.
I don't intend to run the 3CX with that many users per server, so probably using an SC32 license for every server/300 users should be fairly safe.
Thanks for helping gel that in my mind. Do you see anything wrong with my rationale?

One 3CX instance can easily handle that volume if you give it enough horsepower.

 

[MaxDaemon]

True, Centrex, but I like the idea of having it split up and only having 300 cust down at a time, rather than all 1200. Not that it's really been an issue, or at least it wasn't until I said that.

 

[AWS2P]

FWIW , I use basically a ratio of 1sc for 3 extensions when it's not for an extensive use.Until now never been traped with that way to go

 

[N_G]

Howdy, and Happy New Year!

I've done quite a bit of searching and can't find any kind of rule of thumb that tells me how many SC I should need on the basis of how many users I have.

So, as a for instance, suppose I have 50 users. Obviously I don't need 50 SC for those users.
I'd think I could cover 50 average users with maybe 8SC? Maybe even 4SC depending on their kind of business?

I'm also not finding any kind of report that tells me the maximum number of simultaneous incoming/outgoing calls I'm getting.
Is there a report for that and I'm just missing it?

Thanks for any help you can give!

SCs include internal calls, queued calls etc. So for a 1000 users you need more like 256SC. If there are all single users you might need less but if they have a queued call that's 2SC right there. So I think anything less than 196SC will not work. You can certainly split it up over 3 servers or maybe 2.

 

[VoIPTools]

Life becomes more complicated when you split a company into multiple phone systems. For one, the company directory is only for that instance of 3CX so you cannot have a company-wide directory (unless you build your own via custom development). Also, presence across the bridged connections becomes more complicated. Finally, remember calls across a bridge consumes two simultaneous calls so you may end up collectively needing more simultaneous calls than with a single PBX. In my view, one larger PBX is easier to administer, upgrade, etc.

In the past there may have been an argument for splitting the company into separate phone systems --IF-- the company had multiple locations. The idea being that if the internet went down for one site, the rest of the company would remain functional. But today I would recommend hosting a single instance at a major provider (AWS for example). The risk of their entire infrastructure going down is low and bringing up a new instance in the case of a catastrophic failure (using HA, or manually restoring a backup) only takes a few minutes.

I think your complication is with porting phone numbers. I'm not sure how you would do that a little at a time if you have a general number for the entire company. Perhaps you could bridge the old phone system and the new 3CX using a generic SIP trunk and move people over as time permits? I would talk to 3CX support to see how much help they can provide with setting up the bridge.

 

[MaxDaemon]

Mathew, you certainly bring up some good points. I wasn't aware, until I started this thread, that an "SC" isn't quite as simple with 3CX as it was with our previous. You bought an extension license, and that's all you had to worry about. The only thing you thought about so far as "SC" was having enough 'lines' available for all the extensions to use. The system also has a large number of nice clear graphic displays as to current and past phone/line usage and metrics on just about everything else, something that I sorely miss with 3CX.

In re: your second thought regarding the splitting of the systems. It's not quite that, we actually run our own hosting system. Those 1200 users are scattered among a couple hundred companies. We have three servers running in the hosted system with a total of about 2200 users, but only about 350 companies.
In our case, we're also a CLEC, so we have our own SIP system and provide all our own technology, if you will. That makes it very easy to pick and choose among the users to assign DIDs and the like.
The plan right now is to put all new customers on 3CX and to slowly move customers off the existing infrastructure over the next two to three years.

I do like your idea regarding the licensing and how inefficient it would be to have sufficient overkill on each license to handle the worst case. We might need 10 SC32 (on 10 servers) vs 1 SC256 on one server. Of course, the fact that one user might need multiple SC licenses kind of blows my ratio out of the water, too.

Much to consider. I'll also check out VOIPTOOLS. I think you said you had some report generators that did more than the default 3CX ones.

Thanks!

 

[VoIPTools]

That is a very complicated environment. You have a lot of people here in the forums who can help.