Skype for Business telephony is not a complete solution without having an integration with Exchange Unified Messaging. The Exchange UM server can provide many features like Call Answering, Outlook Voice Access, Auto Attendant and Fax Services, however the Fax services are not available with Exchange UM 2010 what I used for the integration below.
To do the integration you have to do the followings:
First of all, you have to make the UM server to communicate via TLS too not just via TCP by default:
Because the TLS has turned on you need a certificate for sure. This certificate must be from the Trusted Root CA and there are no other requirements for SANs or keys.
If the certificate is ready, then you have to assign it to the UM service on the server. The certificate could be valid just if the certificate revocation is working and the UM server is able to communicatio with the distribution server on port 80.
Just browse your UM server in the EMC (Exchange Management Console) and do the assignement using the GUI.
You can also do it via Powershell with the Enable-ExchangeCertificate commandlet.
The next should be the UM dial plan.
During the setup you hae to assign the UM server to the Dial Plan
After the UM Dial Plan has been created then you have to define the subscriber access for the service. Be careful, here you also have to add the phone numbersin E.164 format!
If everything is done you can customize your UM Mailbox policy also in the EMC like PIN policy etc. And be ready to switch to your Skype for Business Front-End server and launch the OcsUmUtil.exe which:
You can find it: C:\Program Files\Common Files\Skype for Business Server 2015\Support\OcsUmUitl.exe by default:
Depends ont he size of the environment the loading could take several minutes! Once it finished you should see your previously configured dial Plan.
And last but not least, the final step is run the ExchUCUtil.ps1 script ont he UM server which is located C:\Program Files\Microsoft\Exchange Server\V14\Scripts by default
Sometimes, you have to run it twice to get the proper result: