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Hosted PBX - Trunk Capacity to Subscription ratios?

Posted by gweinreb on Mon, 09/15/2008
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Thirdlane platform General Questions

Hi,

I'm using MTE in a Hosted PBX service offering sort of context, as I imagine many of you are, too...

What kind of ratio of subscribed "users" and or Tenants to the number of trunks and/or concurrent call capacity do you all establish?

In other words, you have Y number of tenants with an average of X extensions per tenant, for approximately X times Y possible concurrent calls. How much concurrent call capacity would you expect to require? Certainly you play the odds and do not expect them all to be "on the phone" at the same time...

Or do you just "wing it" and when you begin to approach limits increase your capacity? If so, what does that ratio of actual users to necessary capacity turn out to be?

I'm developing business-plan like Cash Flow projections and am trying to figure this out...

Regards,
Gary

Submitted by realbass1 on Fri, 09/19/2008 Permalink

Hello Gary,

I've had a few clients who offer a hosted PBX service. IMO, it really depends on the type of customers you have and how you terminate your calls. I had a client with a single PRI and we had him use a third party IAX terminator to handle his outbound calls when his PRI was full. We took a look at the call patterns, and he was able to get away with having 35% of the channels available vs. his actual subscribers. This is not a recommended setup. I generally try to get clients to have at least 50% depending on their setup and the type of customers they have. If you serve mostly businesses, it's better to have over 50% of the subscribers.

Submitted by eeman on Sat, 09/20/2008 Permalink

the technical term you are looking for is subscription ratios, and the fewer channels you have available ,the lower the subscription ratios you can utilize. Your business model impacts this too. Are you limiting call paths to tenants? or can every extension within a tenant pick up the phone and talk to the outside world without worry of limitation?

Submitted by raven on Mon, 09/22/2008 Permalink

When people complain you'll know it's time to build another 2 boxes. One for the customer side, and one to act as a tandem for the one you have and the new one. Where that point is depends on your server hardware and codec choice.

Submitted by dbenders on Fri, 10/03/2008 Permalink

Hi, in my opinion, you can use a ratio of 1 to 4 or 1 to 3. That means that if a customer needs 100 extensions, the avarege of concurrent calls will be close to 25.

Of course this apply to customers that use the PBX for a normal office. If the customer is a call center, the ratio will be 1 to 1.

This is what I can tell you with my experience.

Submitted by eeman on Fri, 10/03/2008 Permalink

ditto that on call centers. If a call center had 50 agents and there were never more than 20 of them on a call at any given time its time to fire at least 25 agents :). This is also why all the competing telecom bundle pricing (like 10 lines for $100 or $200 a month) always makes exclusions for call centers because normally someone buying 10 lines uses an average of 3-5 at any given time.