Just in case you can't connect to the GSCH server after June 19th, you need to make sure that you are running the correct Raidcall client version. This can be checked via the System icon in upper right corner of the client, select Help Center > About Raidcall to see the version.
To force an update if needed, just select Sign Out from that same icon and the client will autoupdate when you sign back in.
Dear RaidCallers,
Greetings! We are proud to announce important news that the RaidCall servers will be updated on 19th June. In the meantime, the program RaidCall will auto update to V7.3.6. Please be informed that clients lower than V7.3.6 will not be capable of connecting to our new RaidCall servers. If your RaidCall haven’t updated to V7.3.6, go ahead and download it at: http://www.raidcall.com/download.php