Skype for Bus. Ext Communications settings. Office 365.

Hey Guys, 

Kinda of a dumb question but well sorry. So i want to make sure i understand the Skype for Bus ext communication settings, tenant wide vs user. 

1) If i completely disable external contact communication for Skype for Bus and/or Public IM. Will that specific setting override users settings? 

2) What is the relationship / priority of User Settings vs Tenant Wide Settings? Which takes preference. 

I see a lot of documentation out there that covers both user settings and tenant settings, but nothing that explains the relationship/precedence of the two different settings. This is all for Office 365 only, no on-prem skype servers. 

Thanks, 

Robert