What is an unassigned number?

It is a number that you own but not assigned to a user or service. It can be a brand new number from your organization’s number block that was never assigned to anyone or it could be a number of a former employee or a application (like Auto Attendant) that is no longer in service.

Why should anyone call an unassigned Number ?

The most common reason is that, it used to belong to a former employee. Think of – sales and service organization. If an organization has contractors or interns that had a number for a short period of time then it is possible that clients have that number.

When a caller (potential client) calls an unassigned number it will simply disconnect – it is a bad experience.

Solution -> Have an Auto Attendant answer the call

You can have an Auto Attendant answer the call with a message and then redirect the call to your company’s general purpose number.

Here is how you do it with Team’s Direct Routing and Audio Codes.

Note that this feature is available with teams calling plan using powershell commands.

Step 1


Create two call setup rules in a unique Rule Set ID. The action value will be the number assigned to the auto attendant that plays the greeting/does the call handling for unassigned numbers.

Step 2


Assign the Call Setup Rule ID to your alternative routing rule and update the Destination IP group to be Teams

Under the hood, this is what happens –

The request for the incoming call gets redirected to the SBC (AudioCodes)

The call tries all three options in the proxy set as expected.

Then it moves to the alternate route where the destination number has been manipulated to be +18035558001.

This number is the target number of an Auto Attendant.

Therefore, the call gets answered by the Auto Attendant.