My company provides Skype for Business services on VMs in our own hosted datacenters, for customers who don’t want to host themselves on premise. We deploy a per-customer instance of SfB server for each customer and when customers are currently running their own servers on-prem it usually is quite simple – they have server licences per Front End server and CALs for all the users. All of these come under licence mobility and we are a mobility partner so can transfer all that over to us.

The problem is where we have customers with O365 USLs and no on-premise service. Although Microsoft offer Skype Online under O365, some customer still want a hosted server version with us for many reasons and don’t want to use SfB Online (which is also EOL soon of course now we have Teams). What isn’t clear is in this case, what licences do they need?