Home » Skype for Business » Skype for Business Online CloudPBX–Calling Plans and Consumption Billing Explained

Skype for Business Online CloudPBX–Calling Plans and Consumption Billing Explained

I must admit, I thought this topic was well understood, but it seems I am having the same conversations over and over, so possibly worth a blog post. First up if anyone has done this already, I apologise, I did Bingle first, and your page did not show on Page 1, I didn’t check page 2, sorry! Anyway, you should have made your SEO better! Smile #Joking.

A question I am getting a lot is:

What is Consumption Billing and do I need it?

Before I answer this question, it important that you first understand the concepts of Cloud PBX licencing.

What does the CloudPBX Licence Give You?

To begin with, CloudPBX is a licence SKU within Office 365. This is available as an add-on licence to existing E1 or E3 plans or inclusive within E5 plan. It is a “per-user” not a “per-tenant” licence, and each user that you want enabled for CloudPBX must have a unique licence applied to their Office365 account. So when you assign this licence to a user what does this user get?

Well on its own, not a great deal visually at least. But it does unlock the user to access some core CloudPBX services:

  • Dial Plans
  • Voice Routing Policies
  • Hybrid PSTN Calling
  • Azure Voicemail

The most notable feature here is the enablement of Hybrid PSTN Calling. This licence allows you to move enterprise voice users from on-premises Skype for Business to Skype for Business Online and still provide PSTN calling capability to these users via existing on-premises gateways. This is the same for existing Skype for Business hybrid setups, or using Cloud Connector Edition.

CloudPBX licence on its own does not give you any of the following cloud voice services:

  • Cloud DIDs
  • Cloud Service Numbers
  • PSTN Conferencing
  • Organizational Auto Attendant
  • Call Queues
  • Cloud PSTN Calling

What if I need PSTN Conferencing?

One consequence of moving a user from On-Prem to Online is that you change the location of conferences organised by the user. Instead of being hosted on-premises, they are now going to be hosted in Skype for Business Online. This poses some considerations for you. You may have deployed a dial-in access number to your on-premises Skype for Business conferencing service, you may have procured special conferencing SIP trunks for that service too, with several numbers in different regions for localised joins. These cannot be used to access organised conferences in Skype for Business Online.

As there is no such thing  as Hybrid PSTN conferencing, you cannot reassign dial in access numbers to the Skype for Business Online ACP service and “proxy” these via on-premises gateways like you can do with a user DDI in hybrid voice. This means that when you move a user over with just a CloudPBX licence, they are only able to organise web conferences. However, they are able to join PSTN conferences organised by someone else (e.g. on-prem user).

There are three ways in which you can enable PSTN Conferencing for a CloudPBX licenced user, in order of expense:

  1. Create a resource account on your On-Premises pool and provide details to the cloud user and they can organise on-premises hosted conferences using the Web Scheduler service and invite their cloud account as a presenter
  2. Add Microsoft PSTN Conferencing licence to their Office 365 account
  3. Bring Your Own ACP (BYOACP) service to Office365 provided by Intercall, PGi, BT Meet-me services

Expanding on the Microsoft PSTN Conferencing Licence, this is again available as an add-on to E1 and E3 plans or inclusive to E5. It is independent of the CloudPBX licence and if you have users who are not enterprise voice enabled, but require PSTN Conferencing, then this licence can be purchased / assigned without CloudPBX.

What does the PSTN Conferencing Licence Give You?

This licence grants you access to the Microsoft PSTN Conferencing network. This network consists of local PSTN dial-in numbers in over 96 (at last count) countries worldwide. This means you can host conferences in the cloud and provide cheap to no cost dial-in solutions for your participants / customers. The access numbers are Microsoft owned, and are shared amongst all Office 365 tenants / organisations consuming this service. By default, users are assigned a primary number based on the location of the user derived from their Office 365 account citizenship, but participants can join from any one of the 96+ regions using localised geographic numbers.

The PSTN conferencing licence therefore gives users an “All You Can Eat” dial-in PSTN conferencing service, without having to pay a rental fee, plus call rate minute charges, and it could work out significantly cheaper than traditional ACP providers.

However, what if you want to provide toll-free access numbers, or need the ability to dial out of a conference?

There are a few certainties in life, with one of them being “There is no such thing as free”. Therefore, for Toll-Free (TFN) dial in access, some one has to pay. Traditionally, TFN is free to the caller only in the region where the number is regarded as a TFN (i.e. 800, 888, 877 are U.S TFNs but if I call them as a UK citizen, they are chargeable to me as well), but the call charges are reversed to the custodian of the number i.e. your organisation, usually on an agreed rate card. With TFN Service numbers assigned to PSTN Conferencing in Office365, this is no different and if you want this ability, you also need to setup what is call consumption billing.

If you want to use dial out PSTN Conferencing and there are some scenarios where you will probably need to:

  • Transfer the conference to your cell phone (if you’re on the move)
  • Invite someone into the conference on their behalf, buy calling them out of the conference

Then, you also need a mechanism to pay for the outbound call. Like TFN payment, consumption billing is required. Keep this in mind for later…

What if I need PSTN Calling?

PSTN Calling is an add-on licence required for users who need enterprise voice calling features in the native Microsoft cloud i.e. not dependent on on-premises infrastructure like hybrid voice users. Currently, PSTN Calling in Skype for Business Online is available in a handful of countries and this is ever expanding (hence the ambiguity here). Like the Cloud PBX licence it is an add-on licence to existing E1, E3 and E5 plans. Yes that’s right E5 alone does not give you this licence! However, it differs slightly as a Calling Plan licence has a dependency on a Cloud PBX licence. This means to consume a calling plan licence the user must first be assigned a Cloud PBX licence.

The easiest way I can explain this is by comparing Cloud PBX with a Calling Plan licence to a mobile (cell) phone contract. You sign up with the provider for an agreed device and allocation of inclusive minutes and texts and you pay the agreed amount. That amount is split to pay the cost of the device, and the cost of the inclusive calls. The Cloud PBX licence is akin to the device rental and the PSTN Calling plan is the amount that you pay for your inclusive minutes per month.

Back to PSTN Calling plans… Depending on your country and availability, you have the choice of purchasing 2 licence models:

  • Domestic Plan
  • International Plan

For most countries the domestic plan includes 1200 minutes per calendar month that a user can consume to call numbers within their country. The U.S are slightly more spoilt, in that they get 3,000! They must talk a lot more than the rest of us! The International calling plan is slightly more complicated to understand. The international plans allow you to call numbers outside your country as well as domestic numbers. All international plans have a cap of 600 minutes for international numbers and the same amount of domestic minutes as that of the domestic plan i.e. 1200 for some, 3,000 for the the U.S. BUT and this is a BIG BUT the plan is 1200/3000 minutes domestic OR 600 minutes international, key word is OR. This means that the plan expires when either pool of minutes have been reached for that month. For example, if you make 600 minutes of international phone calls in week 1, then your plan is empty and you cannot consume the domestic minutes from this plan until it renews, the next calendar month!

Fortunately there are a few safety mechanisms in place. The first one is that all PSTN Calling plans are pooled at tenant level. This means they go into a big pot that all PSTN Calling enabled users can consume. So if one person runs out of minutes, and another is under utilising theirs then they can be consumed by the heavier user. The second is consumption billing….

What does PSTN Calling Licence Give You?

Before we delve into consumption billing, lets talk about what a PSTN Calling licence gives you. As mentioned before, it has a dependency on the Cloud PBX licence and like this licence needs to be purchased per PSTN Calling user, not per tenant. You cannot buy one PSTN Calling licence and share it out over multiple users!

There are a few things that happen when you purchase a Calling Plan licence. The purchasing (not assignment) of the licence(s) unlock all the Cloud PBX calling features:

  • Service Number Acquisitions
  • Subscriber / User Number Acquisitions
  • Call Queues
  • Organizational Auto Attendant
  • Cloud Basic E-911 capabilities

Now you’re able to port numbers into Cloud PBX from legacy carriers, acquire pools of DDIs and Service Numbers from Microsoft and assign to users and services. There is a formula that is applied on number acquisition from Microsoft. For every 1 x PSTN Calling Plan purchased, you get 10 extra numbers you can acquire and apply to services such as OrgAA, Call Queues and PSTN Conferencing as well as 1 per licenced user. However, if you port your existing numbers, there is no limit to the amount of numbers that can be assigned to your tenant. However, bear in mind that you can only assign numbers to users who have a PSTN Calling licence applied to them. You cannot port a number and assign it to a hybrid voice user (that just wouldn’t work!).

Lastly, the PSTN Calling licence allows calls to route between PSTN and the cloud user who has been assigned it (normal phone call).

PSTN Calling plans on the face of it seem a bit expensive, especially in the licencing model adopted by Microsoft. People ask, “why can’t I just buy one licence and it is a tenant licence rather than per user?”.

I don’t have the answer to this question, I am not Microsoft! But I can hazard a educated guess. The PSTN Calling Plan lights up a lot of cloud voice features, of which in other licence SKUs are not chargeable (OrgAA, Azure VM, Call Queues, SBCs, Network etc.) Running those services at scale has a cost associated. Number acquisitions for both service and DDIs, the rental of these from carriers also carry a cost. The use of the PSTN carries a cost too. These costs have been wrapped up into what you see as a PSTN Calling Plan today.

But cost is a major decision driver and anything we can do to reduce overhead is worth talking about! A lot of companies look at PSTN Calling licences and figure “my staff need to make international calls, so I must by an international calling plan for each of them”. This, if true would give the staff a liberal service, but it would not be financially viable for the company to consider.

Instead, perhaps a subset of users are heavy international callers and it is cheaper to purchased inclusive international calls for these. Perhaps another subset of users are occasional international callers, and the rest are domestic callers. It is the subset of the occasional international callers that you focus on to investigate other ways of providing this calling service without the cost of it upfront. When profiling these users out, there will be a lot of maths and algebra involved to figure out the optimum strategy, but for those where it would be cheaper to use Pay As You Go international calling rather than planned calling you can adopt consumption billing for these users…

So What is Consumption Billing?

Consumption Billing is a licence of sorts applied to your tenant by default once you have purchased Cloud PBX and / or PSTN Conferencing licences. Unlike all other licences this is a tenant licence, in that is unlimited, but is still required to be assigned to a user. What consumption billing allows you to do is top load your tenant with funds that can be used for “out of plan” calling services. A pre-paid credit card for a better analogy. Unlike other plans, it does not expire / renew on a monthly basis, it is there until the balance reaches £0, at which point you load more funds.

How is Consumption Billing Used?

Lets go back in time a little to PSTN Conferencing. Remember I said that if a hybrid user or a PSTN Conferencing user wanted to make a call out of a conference e.g. to transfer to their cell phone, or dial in a participant on their behalf? These calls need to be paid for. The cost of these calls comes out of Consumption Billing!

Remember the use of Toll-Free numbers for conferencing or other services (Call Queues, OrgAA)? The cost of the inbound call is charged back to Consumption Billing! If your balance is Zero in consumption billing, Toll-Free numbers will not connect when called!

Now onto PSTN Calling and those occasional international callers. Instead of purchasing an international calling plan, you can purchase a domestic plan and use Consumption Billing to fund their international calls. The cost of these calls are priced using the consumption billing rate card (https://query.prod.cms.rt.microsoft.com/cms/api/am/binary/REDTZ9).

There are different rates based on the origin of the caller, the destination of the callee and the service called (landline, mobile, premium).

By default users who are assigned a domestic only calling plan are blocked from making international calls. Therefore, simply setting up Consumption Billing and assigning it to a user will not turn on international calling. Instead you need to enable international calling on the user’s PSTN settings in PowerShell

Set-CsUserPstnSettings –Identity user@domain.com –AllowInternationalCalls $True

So Consumption Billing is used in multiple scenarios over different services, and this begs the question “How much money do I need to load into Consumption Billing?”

In truth the question is rather loaded, because each organisation will have different calling habits and usage. You could spend days through CDR records and Invoices and doing some math calculations with the assistance of the top grads from MIT or you could use the recommended table from Microsoft based on the number of licenced users

Number of Licenced Users One time Funding (initial stake) Renewal Trigger
Less than 250 $1,000 $200
250-500 $1,000 $400
500-1,000 $2,000 $500
1,000-5,000 $3,000 $1,000
5,000-10,000 $5,000 $1,000
10,000-50,000 $10,000 $1,000
50,000-100,000 $15,000 $2,500
100,000-200,000 $20,000 $2,500

After the initial loading of funds, consumption billing can be closely monitored to work out actual spending which can then be used to determine what the reload amount should be.

I hope this helps people understand how the licencing of Cloud PBX and its features work.


  1. I’ve been unable to find an answer and thought this post might cover it but I’m not sure so will ask. I have just added the feature to our tenancy on top of E3 and all seems to work OK. However, I’m not sure (in the UK) if our 20 hours includes calling to UK mobiles as well as, obviously, UK landlines.


    • Hi

      If you’ve purchased the domestic calling plan you can call UK landlines mobiles, non-Geographic and service numbers. You cannot dial premium rate. For those you need prepaid credits.

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