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The hidden costs of a PBX that nobody considers...

Are you aware of them? 

When considering a new telephony system, most people look at the cost of:

  • the physical phone
  • a license
  • the install
  • the servers & storage for any virtual elements
  • peripherals

BUT, one simple thing that is often missed is the running costs, environmental impact of physical phones and the power consumption - even whilst sat idling!

Through my 20 years experience, I’ve seen many procurements, helped build some, consulted on moving to Teams or Softphones, and at times even I forgot this major cost and environmental impact.

A recent meeting with an ex-colleague prompted me to look again at this and explore the actual costs. 

I’m not here to vendor bash - and I’m not going to name any - as there are elements to some vendor's products that reduce power when not in use and others that help with power reduction. However, if your PBX is ageing and outdated, then I'd like you to consider those devices.

My aim is to show you the hidden costs to help to you either move your procurement onto the next stage, or enable you to drive your organisation into a more software-based solution: enabling better customer experience & hybrid working, as well as a reduction in carbon & electricity costs to help with the green agenda.

So, let’s get into it!

A typical PoE (Power over Ethernet) phone deployed at this time will range from 3.12 Watts to 15.4 Watts at the higher end of the scale. I've picked 6 different phones that I know are deployed en masse across the Further & Higher Education sector. 

If we consider the average cost of electricity today (24/05/2022) is 17.73 pence per kWh, the results are surprising.

As an example:
Let's say a “Fictitious College Scotland” (FCS) has 1,000 Full Time Employees - plus more support staff.

If we assume:

  • all staff have a phone - that’s 1,000 phones to power.
    This excludes
    the cost to run the PoE switch, it's just the IP phones
  • all staff are back in the college working
    Through my experience, I know that on average 14-16% of users will actually use the phone provided, BUT each phone still needs to be powered for use.
The figures for the 6 phones chosen, look like this:

Typical power usage

Out of hours usage

Average Electricity cost (24/05/2022) pence per kWh

Typical power usage (10 hours)

Out of hours usage (14 hours)

24-hour cost

Emissions (kg CO2)























 Not listed







 Not listed













A typical deployment of 1,000 phones will cost between £12.08 per day to £71.31 per day (depending on the choice of phones). So:

  • £12.07 per day for 1,000 phones = £4,410 per year – and 19,240 Kg CO2
  • £71.31 per day for 1,000 phones = £26,029 per year – and 94,960 kg CO2

As there are too many variables, the calculations above do not include the cost of the PBX hardware, servers or PoE switching, or the many physical elements that can be inter-changed, such as servers and storage options, especially as some may even have multiples gateways per site.

Based on the quotes we receive, which do vary depending on scheme/company - offsetting this carbon will cost between £150 to £600 per year, so reducing the number of handsets will save between £4,000 and £27,000 per year depending on phone, manufacturer etc. Again, this doesn't take into account the reduction of the power usage form the PoE switching infrastructure.


Deploying a softphone on a PC/Laptop will reduce the power consumption for many organisations, especially if that is cloud based like Microsoft Teams - both as the PBX or as the endpoint linked to your current PBX or hosted phone system such as 8x8 or Gamma Horizon.

It will also:

  • Enable or enhance hybrid working
  • Deliver better staff and customer experience
  • Drive innovation (if you deploy the right technology to support this)
  • Reduce your carbon footprint 
  • Help towards your green credentials.

Laptops and PCs are already being powered, so the additional power consumption is negligible. Therefore, not only is there a saving in terms of power, but also in the carbon output of the college.

At the start of the Pandemic, to support the now expected hybrid working model, we saw Microsoft Teams rolled out at pace for teaching, learning and collaboration, so voice can be an extension of that at little extra cost. Other options as listed above will all support the power and carbon reduction.

Drive for change...

At COP26 we saw electric vehicles being used to combat the use of fossil fuels. Additionally, the Police are bringing in a raft of electric motorbikes – these are all charged by generators that are out of sight and out of mind. Perhaps, they're using biofuels, but they need to be manufactured at great cost and carbon. 

We also regularly hear about leaders from around the globe flying on private or jumbo jets - burning tonnes of fuel per second - to talk about the reduction in the use of fossil fuels. Have we seen a change from this? Is there meaningful change coming? Who will drive that change?

As a sector, we can drive that change and show the world how technology can be used to deliver simple changes that can make a major contribution to the climate today. Imagine if 5 colleges, like my FCS example, moved to Microsoft Teams and used Headsets - this could save a fair chunk of carbon, and the whole sector a fair amount of money in the long run.

What's next...

Charterhouse can help you with the audit, planning and migration to new technologies, be that Microsoft Teams or another cloud application. We can help map savings and functionality needed for a service or a product - be that a move to Microsoft Teams in it’s simplest form, or a complex deployment with PBX integrations, contact centre, reception, emergency call devices, LAN, WAN and security integrations with a fully managed or self-managed option. We don’t have a one size fits all approach - we’ll take the time to build the relationship and have the knowledge to support you in the way that best fits your needs and working practice.

Fancy a chat to understand the hidden costs with your PBX? 

Book a call now! >>


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