We have our Skype for Business Online settings to allow external Skype for Business organizations but it's locked down to specific domains for security reasons. We've never had issues joining external Skype for Business meetings from users who aren't in our domain exceptions list while using the Skype for Business client. I've setup our first Skype Room System running version 126.96.36.199 of the app. We've discovered that any externally hosted meetings we try to join using SRS fails if the domain isn't in our exceptions list. It will attempt to connect to the meeting and then drop back to the main screen still listing the meeting with the option to join. Now if I add the external meeting organizers domain to the exceptions list, it works fine. We've tried both having the meeting organizer send the meeting request to the SRS and forwarding the meeting request from an internal account. I went through and enabled external meetings on the SRS Account calendar as well as the option to not delete the comments.