Forum Discussion
External User Sent a Message to a Skype for Business User, but User was not part of his Contacts?
Maybe do you have an Open Federation? And please, do not ask the same question in 2 different "Spaces".
- Checked user settings, and those are set to "allow invites but block all other communications", so we're at a lost how this user was able to just start a chat session with our internal user.
"Allow Invites" controls a consumer Skype user's ability to connect with your Skype for Business account but it doesn't affect an external Skype for Business user's ability to connect with you.
Skype for Business (company a) to Skype for Business (company b) communication is controlled by federation rules.
- Open Federation means that any Skype for Business or Lync user from any SIP domain can communicate with you by knowing your SIP URI (usually email address).
- Closed Federation prevents this, however many companies whitelist specific SIP domains.
I would pull the logs from the IM, find this external user's SIP URI, and check if your company has federated with this SIP domain.
- Same thing just happened to us. We are not open federated and this external user is most definitely not on out allow list. Someone must have found a exploit.
