Sooner or later I would find me writing an article like this.
Many of you would say that this is about shamming MS, but ultimately this is my attempt to reach someone on MS that would listen and care with his customers and provide a better service.
Well,…. it an accumulate of small and medium issues that haunt Teams telephony administrators like me, this and escalated on last Friday.

On the 24th April 12:52 CET, MS started hiding the last 3 digits of all CDRs. Yes! on my GraphAPI based scripts that collect the Direct Routing CDRs
and also on the TAC PSTN usage reports


Online you will not see the last 3 digits, and if you click on the export icon you will get the CSV files with the numbers masked.
I could not find any announcement of this action on the usual channels (just like on February that the data from the startDateTime was swapped with the inviteDateTime) and not even a reason to hide them now.
What is my (customers) problem with this ‘hidden number’ feature? Well, let think about some examples:
- Troubleshooting: how can you track down the number that called or was called? let’s think about a company that has a 1000 number block. To exactly whom did the call came from?
- Auditing/security: what exact number made that threatening call?
- Billing: how to charge a client support based on the number of support hours on the phone? and would you pay your Telecom company if the detailed invoice was hiding the numbers?
Solution(?)
What now? The usual:
- Open a tickets at MS we-almost-care Support. Still waiting for the office in India to reopen since there is no escalation/around the clock option. No feedback so far. Maybe because I could not send a recording (PSR) of the issue…
- Report on the MS365 admin center. Right! the one that closes automatically after 2 hours?
Time to ‘think out-of-the-box’!
If Teams CDR hides the last 3 digits of the callerID:
- let’s go to the SBC and add 3 extra digits to every inbound callerID before sending to MS…
- …MS Teams servers will record on the CDR these extra-long number…
- …and then we strip-it from the inbound call before it gets delivered to the users
Does it work? You still need to find a way to clean those extra ‘***’ from the CDRs,
but the numbers are back 🙂

And this is how MS made me lost my weekend!
Final thoughts
Teams telephony is still on is early stages running still in hybrid supported by SfB back-end servers, but I was expecting much more after this time. Let’s hope that Azure Communications would provide a new approach and more stable services.
My advice to all companies whose business rely on Telecommunications and plan to move to Teams is:
- Clearly identify all your critical needs and perform fully pilot tests
- Find a specialized partner on Telephony that can manage this components and SBC for you.
Years of experience in “Teams”, on-boarding and migration doesn’t mean that some know how to handle the VoIP part.
This quick workaround for this issue was not possible without this premise.
Updates
27.04.2022 – Opened an Incident asking MS why this happened
02.05.2022 – MS just updated today the PSTN reports documentation with a number obfuscation section for several countries. There are no links for the countries legal enforcement. And it’s still a total mess:
- I am in Switzerland and I get 3 digits masked and not 4 as documented.
- If you make a call forward or get calls to Call Queues, it will mask the callee (your own number) and keep the callerID (the external number that the call is forward)
09.05.2022 – MS support sent me the link of the number obfuscation. I asked why I was getting 3 digits masked, when the document mentions that Switzerland is masked with 4 digits
2022-05-10T09:36:00.055Z – MS just started today to obfuscate the CDRs in CH to 4 digits making it consistent with the documentation published 8 days ago.
Still not feedback from support regarding when was this change decided,announced and the legal references of the countries explaining that… still didn’t asked why it gets done in PROD ‘on-the-fly’.