Cloud PBX - onprem pstn Connectivity - integration with analog devices

Hi, I'm assuming that there is no existing on-premises Skype for Business environment. In that case you will need to utilise both an SBC and a Microsoft Cloud Connect Edition solution (CCE). CCE will let you create a hybrid voice environment with an on-premises PSTN connection, and is required at this time for achieving what you want. Going forward, Microsoft will introduce a 'bring your own trunk' capability that will enable you to connect directly from the on-premises SBC to the Microsoft cloud, however a CCE solution is still required at this time.

Vendors such as AudioCodes and Sonus both make SBC's with the CCE solution embedded on the appliance (cloud bond and cloud link respectively) for this very purpose. In terms of analogue requirements, again both SBC's come with analogue capabilities if required (FXS ports), although depending on quantity and locations, you may need to procure separate analogue gateways.

You should speak to AudioCodes or Sonus, or to a partner organisation, and have them spec the SBC / CCE appliance out for you - hope that helps a little.

Kind regards
Ben