Simultaneous Call

There is a famous carpentry proverb that states “measure twice and cut once”. The idea behind the saying is to emphasise accuracy when cutting materials. This makes sure time and resources are not wasted during a project. Accurate measurement and planning are keys to any successful creation. This is especially critical for building a communications solution such as a phone system.

Legacy systems dabbled sporadically between total extensions, physical lines into a building, line rates, line rental fees and other arbitrary measures. These systems drove a sunk cost fallacy mindset as they were expensive to maintain, unable to scale and difficult to interoperate with other systems.

The rise of VoIP has given businesses the ability to unshackle from these legacy systems and with 3CX, adopt a superior model of measurement – the Simultaneous Call (SC).

A Simultaneous Call is simply any call between point A and B that is used by the system at any given time.

  • A call between 2 internal extensions – 1 SC used
  • A call between an internal extension and external caller – 1 SC used
  • 1 active call, with 4 callers waiting on hold – 5 SC used
  • 1 call on hold, talking to an extension to confirm they can take the call – 2 SC used
  • 10 hotel wake up calls – 10 SC used
  • 3 calls between bridged 3CX systems – 3 SC used

There are a few ways to estimate the Simultaneous Call count required. I generally recommend an onsite walk-around a couple of times during a workday, to get a rough head count of users on the phone during busy periods. This has the added benefit of scoping how their networking is laid out, and what type of phones the end user may need if coming from an outdated legacy system.

The customer may already have a rough estimate of what SC count they will need. An onsite trip helps confirm or adjust what they may require. This may also be gleamed from some basic timestamp analysis on their existing phone bill, to work out busy periods and how many calls came in during a period of time. A billing breakdown also gives a fantastic idea of the cost savings possible with a modern VoIP PBX system, using SIP providers for calling.

Planning for future growth is also a key factor, when estimating a customer’s SC count. Depending on the type of business, there may be instances when they need to plan for additional call capacity. For example, a business supporting a product may need extra capacity for an urgent product recall. A hotel may need a larger call count for the busy season to allow for a larger number of wake-up calls. A medical practice may need to plan ahead for supplementary queries during the flu season.

Another increasingly popular method is to generate a free 3CX trial that the customer uses in parallel to their legacy system. Trials are easily generated from your 3CX reseller portal. This has the added benefit of reports that can be run within 3CX, to see the call count used over any given day. This allows the end user to experience a live 3CX test system and get a feel for the new functionality on offer.

If you need to talk through a specific site’s requirements, reach out to Matt Carey ( who can offer his experienced insight.

The VoIP team held a recent webinar around the topic of Simultaneous Calls, if you missed out, catch up here.