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Demystifying Costs of Office 365’s Calling Plans

Microsoft Calling Plan

Microsoft’s Phone System Calling Plans make it simple to budget and pay for local and domestic long-distance calls.

It is more complex, however, to track and pay for international calls. Some organizations want specific departments or locations to pay for their own international calls, rather than absorb the costs at HQ or central IT. This blog outlines some tools and tips, with examples from real invoices from Microsoft.

How Microsoft Bills for Phone System Services

Domestic (local and long-distance) calls are drawn from a licensed user’s allotted minutes each month. There are multiple calling plan options, each allotting a specific quantity of minutes. Take for example the largest of the Microsoft calling plans, the $12/month, 3,000-minute plan. Each user of such a plan can make up to 3,000 outbound domestic local and long-distance calls. If they go over, then they can use some of unused minutes of other users who are in the same type of plan. In other words, there’s a slush fund. If there are 10 users in an organization, each with the 3,000-minute plan. the organization has an available 30,000 outbound domestic minutes per month. If the organization exceeds that 30,000-minute total, then a per minute overage is assessed.

Outbound international calls and toll-free inbound calls are billed a la carte. Technically, there is a $24/user/month international plan, but for the occasional caller, it’s not worth it. International calls are more infrequent, billed as incurred, and drawn from a prepaid pool of money that the organization pays Microsoft, called Communications Credits. Information about calling plans and the rates for calling internationally can be found at

By the way, conference calls that allow voice-only attendees to “Call me at” (their local phone number), will be billed as incurred if the conferee enters in an international phone number. The tenant admin can turn off that capability if desired, because allowing “call me at” can run up an unpredictable expense.

The full list of calls whose minutes are drawn from Communications Credits can be found here

The Limitation that Leads to Chargeback

Microsoft limits Communications Credits to only a single payer, the owner of the tenant. Microsoft has no way to determine which users in an Office 365 tenant belong to which cost center or billing address. So, they send the entire usage bill for the entire tenant to one payment address. That leaves organizations with the task of taking one bill and parsing it up into multiple small bills for chargeback.

Dissecting the Bill

Microsoft provides the Phone System bill in a raw CSV format to the owner of the tenant. It includes line items for in and outbound calls, both domestic and international, as well as conferencing and toll-free usage.

An excerpt of the invoice is below, with explanations of each type of entry.

The Call ID column is irrelevant for bill back purposes. It’s a uniquely generated number that Microsoft uses to track each individual call. The IP address is irrelevant, showing which of Microsoft cloud equipment has processed and delivered the call to the Teams/Skype user.

The User ID identifies the Teams/Skype user who made or received the call. This is a key field in a billback scenario, because the User ID can typically be associated with department or accounting cost center.

The Caller ID is the number of the party making the call. The preceding 1 is the internationally-known prefix for all USA phone numbers. You’ll recall dialing 1 on long distance calls from landline phones. The other 10-digits are the area code, prefix, and last four digits.

The Call-Type and Domestic/International fields are the next key fields for chargeback. The combination of pstn_out (column F) International calls (column G) will automatically incur a charge that decrements the tenant’s Communications Credits. In line 869, the call is designated as “International” in column G (made by user2), and the cost for that call was $0.01 USD. *Those* are the calls for which MSFT will bill the tenant owner for the minutes used. Those calls should be included in a process to track/invoice back to the department that made the call.

Other Call-Types:

pstn_out Domestic are the outbound calls that are counted against the caller’s allotted # of minutes. Each MSFT calling plan has a set $ of domestic minutes from which these calls are debited from. User1 made four outbound calls from 5436255178 in lines 865-868. As long that user stays under their allotted mins/month, there are no additional charges to bill back for these types of calls.

pstn_in calls are indeed free. In line 860, user1 got a call from 13027872600 to his #, (543)625-5178. The call lasted 7 seconds and didn’t incur a fee.

conf_in calls are calls into that user’s conferencing bridge. User1 hosted conf calls (like lines 861-862) which were joined by outside users each time (13028794400). There are no charges to bill back for these calls (unless User1 goes over the 3000 mins/mo each licensed he is allotted for conference calls where an outside phone calls in).

pstn_out_forwarding calls get logged when the user forwarded the call to an external phone number, like their cell phone. They are not charged as long as 1. The forwarded number is domestic and 2. The user is not over their 3000 domestic minutes / month.

The Destination # is the number of the called party. The Start Time and Duration are relevant for billing analysis or disputes. Finally, the “Charge” column shows how much was decremented from the Communications Credits for each call. Since most calls in this excerpt were domestic and show no charges, the 23 second call to Italy has resulted in a $0.01 charge.

Additional info about these fields can be found at

Other gotchas

* An organization may have idle calling plan licenses that are currently unassigned. For minutes to be allocated to the pool, the calling plan license must be assigned to a user. Having 20 licenses, but only 10 assigned, only allocates 30,000 minutes, not 60,000. Overages would occur after 30,000 minutes even if there are additional unassigned calling plan licenses.

* To use Communication Credits for International calling, a tenant still requires a single International calling plan, assigned or unassigned, to enable International calling within the tenant.


No organization wants the overhead of charging back for nickels and dimes. Yet international and toll-free charges can add up. The moment a department starts taking toll-free calls from wireless phones in Estonia at $1.29 / minute is the moment central IT would want a chargeback mechanism.

Strive towards simplicity but prepare for complexity when budgeting for Phone System chargeback and other surrounding support services.

Work with our team of Cloud Computing Consultants who have done this so many times they know all of the “minefields” to prevent missteps.