Posted by: Mike Clarke


When examining a new or existing telecoms tariff there’s a lot to look at. When undertaking a high-volume dialling campaign, overlooked micro charges, small charges at a fraction of a penny, quickly accumulate into an unexpectedly large bill. In this post we look at the common charges that make up an outbound call centre’s monthly phone bill and the things to watch out for when choosing a telecoms provider.

Bundled Calls or Price Per Minute

Some telecoms providers offer the option of a bundled price per month for a fixed block of minutes instead of a price per minute for calls. This can be quite tempting as, provided the deal matches your needs, you’ll have a predictable phone bill every month.

However, there are a few gotchas to watch out for.

Bundled Minute Tariffs

Firstly, these are based on much smaller scale domestic and small business tariffs where the number of calls being placed each month is usually small. Even where customers make full use of these tariffs, the number of customers utilising very little of their monthly allowance offsets them many times over. This means that providers can offer what seem like very generous deals knowing that most of their customers won’t come close to using their minutes allowance, ensuring healthy profits for the provider.

When applying these assumptions to outbound calls centres, there’s usually not such a thing as a low-use user. All the minutes will be likely be used in full meaning that there’s far less profit, and possibly even a loss, for telecoms providers supplying outbound call centres with bundled minutes. To avoid this scenario, most bundled deals come with “reasonable use” clauses, which effectively rule out their use for call centres. Even if there’s nothing explicitly stating that they can’t be used within an outbound call centre environment, they’ll often be restricted by a calls per minute limitation or similar that renders them unsuitable. This is understandable as otherwise the provider is likely to lose money if the bundled deal is too generous.

In situations where a bundled calls deal is geared toward call centre use, there can still be pitfalls. Once you run out of minutes in your bundle, it’s standard practice to transition all further calls in that month to a pay-as-you-go model at a significantly higher price.

For example, if you have a bundle that includes 120,000 landline minutes at £600 per month, you would be paying just 0.5 pence per minute. Let’s say the bundle includes a clause that says that after you use your bundled minutes the price increases to 1.5p per minute. If your total minutes used in a month come to 240,000, this would mean that your bill will come to £2,400 with an average rate of 1 pence per minute, which is considerably higher than most providers landlines rate and definitely not a good deal for your business.

This is not dissimilar to being offered a “new customer rate” which increases part way through the contract. You need to consider both the reduced and full costs associated over the full term of your contract to work out your actual forecasted costs.

Lastly, bundled rates often come with contractually binding terms of between one and three years and provide little recourse if the number of seats, and hence the number of minutes required, drops during the term.

At Greenlight, we much prefer billing by the second, with a low cost per minute and as few additional charges as possible so that your call charges adapt to your requirements as your business needs change and fairly reflect your use.

Cost Per Minute Tariffs

If we look at call charges in terms of a price-per-minute, it is easy to assume that all providers calculate your bill in the same way. Unfortunately, this is not the case. Let’s take a closer look at how different providers come to a total cost for each call.

The usual components of a call’s costs are:

  • A connection charge
  • A cost per minute
  • Rounding of the cost per minute
  • A minimum call charge

Connection Charges

If there is a connection charge levied against each call, this can have a dramatic effect on the overall call costs for an outbound call centre. While this may not be significant when looked at in terms of calls where an agent speaks to a potential customer, it will also be levied against all calls that connect but go to an answer machine, which can be substantial. Calls that don’t connect at all will not be subject to a connection charge, but for campaigns dialling predominantly mobile numbers, this will be very few in relation to the total calls dialled.

At Greenlight we don’t charge any connection charge, meaning that this isn’t something our customers have to worry about.

Cost Per Minute and Rounding

The cost per minute is usually the headline rate that you’ll look at when considering a new telecoms package, with the most significant figures being the cost per minute for landlines and the cost per minute for mobiles. Some UK providers are now adopting the US model of charging a cost per minute for taking inbound calls (not just those coming in using freephone numbers), so this is worth looking out for as well.

As outbound call centres generally place lots of short calls that are less than a minute in duration, the rounding is more important that you may first realise. Consider a call centre that places 100,000 calls in a day, 50% of which go to answer phone after 18 seconds with a cost per minute of 1p. If calls charges are rounded to three decimal places, each call is rounded up to a 10th of a penny. Each call that goes to an answer machine costs 0.3p, assuming there’s no connection charge. The 50,000 calls therefore cost £150.

If the call charges are instead rounded to two decimal places, each call is rounded to a penny. This means that 50,000 calls going to answer machine a day costs £500. Over the course of a standard month working Monday to Friday, this equates to £7,350 extra just due to one fewer decimal place.

As you may have guessed from the fact that we’re talking about it, at Greenlight we round all costs to three decimal places and advise any call centre business to watch out for deals that do otherwise!

Minimum Call Charges

Lastly, you need to take a note of any minimum call charges that may be in place on a tariff. While a minimum charge of a penny may not seem like much, this will multiply very quickly in outbound dialling environments. The best way to look at minimum call charges is the number of seconds that they equate to. Let’s take a 0.5p per minute rate as an example:

Minimum Call Charge

Equivalent Seconds


12 seconds


60 seconds (1 minute)


120 seconds (2 minutes)


This means that all calls that last 12 seconds or more are unaffected by a minimum call charge of 0.1p. For those less than 12 seconds, there’s a small premium per call. However, this is dwarfed by the extra charges levied with a 1p connection charge, which means all calls less than 2 minutes are being rounded up and counted as being 2 minutes long.

At Greenlight we have a minimum call charge of 0.1 pence, which is really just passing on the wholesale costs charged by our carriers.

Other Things to Watch Out For

Within large volumes of data, it is common for some premium rate numbers to slide into the mix and for people who own these numbers it is in their financial interest to not only to answer but prolong those calls. Ensuring your chosen platform can detect and avoid calling such numbers could end up saving you a significant amount of both time and money. Avoiding premium rate numbers starting 09 is easy enough, but numbers starting 087 are also revenue generating for the receiving party as are several ranges of 07 numbers.

Similarly, if international numbers can get into your system via web leads or APIs, you could end up with an unexpectedly high bill from calling these as most tariffs aren’t optimised for international destinations unless requested.

In both cases, Greenlight protect our customers by ensuring that calling premium and international numbers are disabled by default with the option to enable individual international destinations on request. We also provide our customers with a monthly breakdown of their top 20 most expensive calls and most expensive destinations so they can easily spot any anomalies or unexpected costs and rectify the issue.

The Importance of Itemised Billing

While traditional phone bills have always included a line-by-line list of all calls made in the billing period, many call centre telephony providers either provide a summary bill (with costs aggregated by destination type or area code), or just skip providing an itemised bill altogether. This leaves the customer vulnerable to discreet or unannounced increases in rates, with no way of checking that call charges are being calculated the way they were led to believe they would be.

At Greenlight, every month, each of our customers is provided with a CSV file containing one line for every call made, the rate charged and the total for the call, so there’s no doubt about where every penny charged has come from.

Charges for CLIs

With numerous UK carriers (mainly BT, Vodafone and Samsung) now blacklisting company’s numbers without warning or recourse, it is becoming increasingly necessary for companies conducting outbound calling to procure a steady stream of numbers to present to the call recipient when you dial, while still ensuring that they meet all regulatory requirements. These CLIs come at a cost and need to be retained for a few months after they are retired so that customers can still call back in on these numbers and your business remains compliant.

The price to acquire these numbers, and the ability to transfer them is important but it is equally important to ensure you get the most value out of them. There are many reasons why you need to replace a CLI, but the common denominator is a reduction in the answer rate. Bad data and dialling aggressively are common reasons why a number may be tagged as a spam or scam call which will substantially reduce the answer rate and increase the turnover of your CLIs.

At Greenlight we charge £2 per CLI per month. Using that figure as an example, if you require 10 numbers, and rotate these numbers monthly and have a retention period of 3 months you will be typically spending £60 on your presentation numbers each month. However, a well-executed dialling strategy combined with detailed connection rate reporting can substantially reduce the rate at which you need to rotate numbers, thus decreasing the number of CLIs required, increasing their longevity, and maximising the number of productive conversations that you have.

Channels and CPS

Lastly, if running an outbound dialling campaign, you need to be sure that your telecoms provider can sustain the level of dialling you’ll be carrying out, especially if you’re using a predictive dialler.

The channels that you are allocated is the number of concurrent calls that can take place at once. If you’re running a campaign with 10 agents and no predictive dialling, you might have 10 channels for your agents plus an extra three or four for inbound calls and/or management placing manual calls through other extensions. If those same 10 agents are using a predictive dialler, you may well require three times that number of channels so that the dialler can operate correctly during periods with a low answer rate. You also need to factor in the time taken to set up and tear down each call as it is placed and ended. Even if a call returns an engaged tone and hence can immediately be logged and disconnected, there is always some time required to initiate and destroy the channel meaning that you’re likely to need more than you might expect if dialling predictively.

Similarly, if you’re running an inbound or blended campaign where you’re expecting a large volume of inbound calls, you’ll need one channel for every call, whether that call is being handled by an agent or is in a queue or IVR waiting to be answered. If no channels are available and a customer calls in, they’ll just get an engaged tone. Not a good look for your business!

CPS, or Calls Per Second, is a critical number to look for in any telecoms contract intended for use in an outbound call centre environment. This is aggregated across all your channels, and if you dial beyond this your dialling system will be unable to place additional calls. This number will need to scale with the number of channels that you have, and many “regular” telecoms providers tariffs don’t come near to the volume required for outbound call centres.

At Greenlight, we’ve got more than enough CPS and channels to go round as we can route calls over multiple upstream providers. This means that for our customers, the system just works and they don’t have to worry about either.


Final Thoughts

Looking at the components of outbound calling rates in isolation can be extremely misleading. What appears to be a low-cost solution on the surface can ultimately lead to a much higher bill down the road, or worse, a call centre that’s unable to function at full capacity. Only by looking at and understanding all the elements of your bill can you make an accurate comparison of the options available to you and accurately model your future costs.

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