Take a look at the November 30, 2015 Microsoft announcement. https://blogs.office.com/2015/11/30/a-deeper-view-into-skype-for-business-cloud-pbx/
Using what used to be Skype, what used to be Linc and Microsoft Office, plus, Cloud PBX, integration with existing PBX units, existing phones, soft phones, Android phones, iPhones, of course having Skype take advantage of number portability and more Microsoft has entered the telephony business.
Let us know if you would like to know more about this offering. Although it will fit many different companies if you are already an Office 365 user and you are also using WebEx or GoToMeeting for conferencing and are considering moving yo Hosted VoIP or Unified Communications as a Service (a.k.a. – UCaaS) you should give this a look.