Hey Hi !
The Skype for Business Edge server is required in the Hybrid setup as it will act like a mediator/proxy between you On-Premise Skype for Business and Skype for Business Online.
This is basically required in order to not to expose your Internal servers to external world and if you want to send out anything outside your company network then it should be via Edge server and this is by DESIGN, since the Skype for Business Online environment
available externally you must need a Edge server to setup a Hybrid.
So lets talk about deploying the Edge server and publishing the service to Externally...
>> Edge server doesn't any kind of IIS service, instead it hosts Access Edge, AV Edge and Web Conference Edge roles (I mean having the Public IP and creating a DNS A / SRV record externally). In your case you need to publish all the 3 roles
publicly in order to have the seamless communication between your On-Premise Skype for Business users and Online Skype for Business users.
>> If you are looking to have only IM and Presence functionality between your On-Premise Skype for Business users and Online Skype for Business users. ; then just publish only Access Edge Role (I mean having the Public IP and creating a DNS A
/ SRV record externally).
Note : Access Edge service is mandatory and you need to publish this service to external, and other services are also mandatory, however it depends if you want to leverage them for specific modalities.
Reference Links :
http://www.rtcpedia.com/Blogs/Action?blogId=10039&blogURL=StepByStepInstallEdgeServer
Now, you need to setup a Hybrid -- refer the below excellent article
https://blogs.technet.microsoft.com/canitpro/2015/12/23/step-by-step-skype-for-business-2015-hybrid-configuration/
So, when you plan for Skype for Business Hybrid, you have to plan for Edge server first !!
Neeranjan Shettar (MyPage)
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