Direct routing to multi tenant users without MS hosted phone numbers

Occasional Contributor



I want to setup a multi tenant system I have read the guide MS supplied but I'm stuck with this scenario. I have my PSTN numbers hosted with my supplier. I want to route calls using direct routing to my customers. 


I want the below:

PSTN > My Platform >  


But my customers either have or domains set to their team users and not my subdomain. So how can I route calls to these individual users or teams as they will not have a MS hosted number that I can route to? 

7 Replies
Best Response confirmed by ThereseSolimeno (Microsoft)

When you write "My Platform" is that a multi tenant SBC you have setup? You have to route the calls to the correct SIP trunk for each customer from your SBC and to the PSTN number of the user, not to the SIP address.


Your customers have to add a subdomain with your domain in their tenant to be able to use your multi tenant Direct Routing setup.




@Linus Cansby My Platform is my existing setup used for my normal VOIP traffic, of which I have added a SBC specifically to deal with MS Teams. This then would give my customers the option of delivering calls to their team users.


In my 1st test but not in a multi tenant setup I was delivering the call to the users sip address using direct routing. Which is really what I expected to do going forward. As I said the PSTN numbers are not hosted with MS but my other provider and porting them to MS is not an option.

So how can I get the calls to the user? Can I add a number to a user / team voice routing profile without actually needing that number to be hosted with MS?



@VoipGuyUK wrote:

Can I add a number to a user / team voice routing profile without actually needing that number to be hosted with MS?

Yes. You run a command like 

Set-CsUser -Identity "" -OnPremLineURI tel:+14255388797 -EnterpriseVoiceEnabled $true -HostedVoiceMail $true 

in the customer's tenant, as documented at .


@Ryan Steele Thanks so that number as long as valid E1.64 is acceptable regardless of where hosted. If I want to be able to send a call to multiple users at the same time how should this be achieved? Can multiple users share the same OnPremLineURI ? Or would I need to manage groups on my platform distributing to each OnPremLineURI that each user would have?


@VoipGuyUK If that number is assigned to a user in another platform (PBX) you should not assign that the same number to a user in Teams. You should decide what PBX you want to use for that number, the old platform you use today or Teams, you can have some users in the old PBX and some in Teams.


If you have multiple users that should answer to calls on the same number the best way is to setup a Call Queue in Teams.


@Linus Cansby Let me explain an example call flow, there are no users on my platform. The below would be an IVR with 3 DTMF Options the first one wanting to deliver the call over direct routing to 2 MS Teams users. The 2nd to 1 MS Teams user and the last to PSTN:



Inbound PSTN Number +44 121 555 8888 > My platform IVR > Option 1 MS Teams User Bob & MS Teams User Alice / Option 2 MS Teams User Claire / Option 3 PSTN Number +44 121 555 9999


@VoipGuyUK Then I suggest that you setup incoming calls to +44 121 555 8888 is send to Teams with Direct Routing (no need to port number to MS). In Teams you should setup a Auto Attendant that handles the IVR.


Each option should then be a Call Queue with the agents as members.