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Unassigned numbers in Microsoft Teams

Unassigned Numbers in Microsoft Teams

Unassigned numbers in Microsoft Teams management has traditionally been a complicated task involving PowerShell. Recently, Microsoft have announced the support for this in their Teams Admin Center. This will no doubt please a lot of customers and will simplify the management of unassigned numbers going forward.

What are the use cases for managing unassigned numbers in Microsoft Teams?

There are several cases and these of course are dependent on the individual. However, the most common case is when a worker leaves the business and their DDI needs to be redirected to a colleague or a team. The other case is when an inbound service has more than one direct number that must be answered by the same workflow.

Redirecting Unassigned Numbers in Teams to Users

Consider a working in a sales team with multiple account managers. These users will have personal relationships with key customer contacts that need to be maintained through staff turnover. When the account manager leaves, the sales manager will want any customer who calls their DDI to be redirected to another account manager who has been tasked with managing the account portofolio.

In Teams, it is not possible to assign more than one direct line to a user. The solution to this has been to either unassign the number from the leaver, convert it to a service number and attach it to an auto attendant that redirects to the nominated cover user. Or using complicated PowerShell Commands to manage the inbound call treatment of the unassigned number.

Choosing the Auto Attendant method carries a lot of technical cost, especially if the number is provided by Microsoft Calling Plans or Operator Connect. The number must be converted from a user number to a service number. Until recently, for Calling Plans at least, this required a support ticket.

The second option of using unassigned number management is more favourable, but requires complicated PowerShell to configure. For more information about this method, check out Martin Boam’s blog article.

How to Manage Unassigned Numbers Using Admin Center

In the Teams Admin Center, under Voice and Phone Numbers you will notice a new tab called Routing Rules

Unassigned Numbers in Micrsoft Teams
Unassigned Number Management in Teams Admin Center

There are different types of rules you can create depending on the complexity of the case you are building. The simplest is to treat a single unassigned number.

Redirecting a single unassigned number to a user in Teams
How to redirect a single unassigned number to a user in Teams

Make sure that you use E.164 formatted numbers in the source number field.

Other rule types include:

Numbers Starting or Ending withApply to all unassigned numbers that start or end with the declared digit pattern
Phone Number RangeApply to all unassigned numbers that are within the declared contiguous range
Advanced SetupApply to all unassigned numbers that match the regular expression pattern supplied

Evaluation Order

The evaluation order is important because it tells the system in what order to process the rule. All rules are entered into a rule table and their position is determined by the evaluation order. Rules with a evaluation order of 2 will be processed before others that have an evaluation order of 10 for instance.

Why this is important is because once a rule is matched, processing stops and the rule is triggered. In more complex unassigned number management deployments you may have a catch all treatment rule for the entire range which would be priority e.g. 100. You may have another rule for a smaller subset of numbers within the range e.g. a subrange block of 20 for sales using a Phone Number Range rule that triggers a different treatment with evaluation order of 50. Finally, you may have a single number rule that targets a specific number within the same overall range with an evaluation order of 10.

This means that you can create cascading rulesets that can apply to the majority while building more targeted rules to meet business cases to suit.

Treatment Options

In addition to redirecting a caller to another person within the organisation, you can redirect them to an Auto Attendant or Call Queue. You can also play a greeting message which is played once to the caller on answer.

If selecting a greeting, you must upload a pre-recorded message. The use of text to speech is not currently available.

Limitations of Unassigned Numbers

If you use Microsoft Calling Plan user numbers and need to redirect callers to an alternative destination, you must ensure that you have sufficient communication credits assigned to your tenant. Routing unassigned Microsoft Service numbers, you must have at least one Teams Phone Resource Account License available.

Unassigned number treatments will apply to both inbound calls to Teams and calls outbound from Teams.

It is not yet possible to redirect unassigned numbers off platform e.g. to an external phone number directly as an option. To mitigate this, you could create an auto attendant with an external redirect and set the routing option of the unassigned rule to select this attendant application.

Unassigned Number Management with Callroute

As a Callroute customer, you can manage your unassigned numbers using our portal. This solution is our own proprietary handling, so any subsequent management you apply in Teams will also apply.

Our inbound number management allows you to quickly assign multiple inbound numbers to users or resource accounts that take effect immediately. There are no complicated regular expressions to learn.

Redirecting A Single Unassigned Number To A User

In Callroute, login and navigate to Numbers and select the range the number in a part of. Click on the Configure icon.

Unassigned Numbers Using Callroute
Number Management in Callroute

Now choose the destination service and / or user to redirect the caller to when called.

Redirect Unassigned Numbers to any user of service connected to Callroute
Redirecting an unassigned number to a user or service

To redirect an entire range to a single number, modify the default inbound route for all the numbers in the range e.g. Call Forward

redirect entire unassigned range in callroute
Redirecting an Entire Unassigned Number Range in Callroute

When configured, any number that does not have an explicit destination service will follow the default inbound call routing path.

Assigning an inbound route on a specific number will override the default to ensure the correct call delivery destination is adhered to.


Callroute’s number management for Microsoft Teams on top of the native capabilites within Teams helps customers manage their numbers more efficiently. Allowing voice admins to quickly change call treatments using a simple interface that makes sense to non technical people.

This is just one benefit of using Callroute. There are many more!

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