The Skype For Business Server is on-prem.The servers are all Windows 2012 R2 AWS instances being connected to via remote desktop.

I have a PBX and PTSN license along with a PTSN phone number.

And I have a PTSN gateway on another server. The mediation server is collocated on the frontendpool(the server running skype for bussiness). I have successfully created a Skype For Business Server 2015 along with a trusted application pool running on a standalone server. It works as intended and now I am working to deploy the application on a server so I can call in using my cell phone to test the application. Up to this point I have been testing the service as I go using xLite on my local machine. An unknown user calls a phone number remotely, from their cellphone, the IVR picks up the call, listens and responds to the user's voice and dmtf tones until they hang up. I have pretty much finished my UCMA application which is designed to be a simple IVR.