Forum Discussion
SfB online migration with contacts
NewlifeMake Skype for business hybrid scenario:
Skype for business hybrid configurationMigrate users from Lync to Skype for business online via Lync control panel or powershell
Moving from SfB on-premises to Skype for business onlineContacts will migrate together, chat history is probably stored in the mailbox
Moving between Lync\Skype for business on-premises, meeting URLs change, so either sent out meetings needs to be updated by the user manually or you can use meeting migration service
Meeting migration service
If the company that you want to migrate uses Enterprise Voice features, you should investigate the needs separately.
NewlifeMake Skype for business hybrid scenario:
Skype for business hybrid configuration
Migrate users from Lync to Skype for business online via Lync control panel or powershell
Moving from SfB on-premises to Skype for business online
Contacts will migrate together, chat history is probably stored in the mailbox
Moving between Lync\Skype for business on-premises, meeting URLs change, so either sent out meetings needs to be updated by the user manually or you can use meeting migration service
Meeting migration service
If the company that you want to migrate uses Enterprise Voice features, you should investigate the needs separately.
If I understand the question right the Lync 2013 is in one forest (Forest A) and the users are synced from another Active Directory forest to Azure AD (Office 365), so there is no Skype Hybrid setup between the current Lync 2013 setup and Skype Online and you need to sync users from Forest A to Azure AD to migrate Skype users. So if there is no hybrid setup from current Lync 2013 you won't be able to migrate users with their contact list.