Unassigned number limit


A questions for MS folks.

Today i started the porting process for one of our smaller offices, after i had completed the form i went to try and acquire a couple more numbers that office will need only to be shown i had no spare licences.

We do have some currently unused numbers we ported from other locations but i had (mistakenly it seems) been under the impression that the limit of unassigned numbers was for the number we had asked MS for and not ones we had ported over. Speaking with support they have said there is a 10 +10% rule for unassigned numbers which cannot be changed.

In my current situation the only way forward i see is to wait for the porting process to get approved so the numbers appear in the portal and i can assign them to users. Going forward though with some of our larger offices i can easily see us having more than 10% of numbers unassigned at any one time (Especially with the current licensing structure), having this limit i fear will be a major roadblock in switching some locations over.


Are there any plans to do away with this limit or allow it to be changed?




5 Replies


This is interesting. My understanding was that if you ported in your own ranges, they stayed on your account regardless of the number of licences you have.


Can I clarify, are you saying (numbers just being for example)

  1. You ported in 100 numbers
  2. You have 50 user accounts
  3. You then want to assign someone a new Microsoft number, but not one from the range you ported in, but you can't because you can't get a new Microsoft number because the 100 you ported in puts you over the "10 + 10% rule


If the above is correct I can see how that would be a blocker. I port 100 in from state X, but only enable 40 users there, then I start a project in state Y that just wants new MSFT numbers, but can't assign them.


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This is a known issue and, yes, it could be a blocker. We would like to handle it better but I don't have anything concrete to announce. In the meantime, I suggest opening a support case when you run into this issue. There might be something we can do for you on the backend.

Thanks, i did have case open but sadly there was nothing that could be done. We have no plans to move our main site to S4B for at least a year so hopefully it will be corrected by then.



Here's a reference KB Article that explains the formula:  https://support.microsoft.com/en-us/kb/3148108

Hi there, I’m the engineering manager behind number management so this topic deeply interests me :) As Doug explained, this is a known issue and I do understand the pain it can cause. So yesterday I brought up this post/topic with the Product Owner’s team and was informed we’ll start tackling this issue in the near future. I don’t have much more details at this stage but this scenario/situation will be considered for the solution. Just to make sure we all understand the porting scenario and its relation to the license count and amount of telephone numbers you can have. Whenever you create a port in order (via our Admin Center or Support), Skype for Business will not block the port to proceed based on the count of licenses. This means that, if you have 50 licenses but wants to port 100 numbers, that will be allowed without any problem. What currently happens though is that your entire phone number “stock” will count toward your license whenever you want to acquire new numbers from Microsoft, so on this scenario, you will have 100 numbers but only 50 licenses (which will entitle you to have 65 number). The 100 numbers you already have won’t be impacted at all and, if you want to port in more numbers you will be able to do so, although attempts to acquire new telephone numbers from Microsoft will be blocked. While the solution to this problem is not available on a “self-service fashion” (where you can do everything by yourself via admin center or PowerShell), you can rely on our support team to help completing your transition. Support team will have ways to give you some temporary numbers so you won’t be blocked. I hope this helps clarifying and please let me know if you have any further questions (or feedback).