So, I hit the Big Red Button now. Too bad, they did not offer any means to tell them what is going on, since
http://scopezoom.com/vox.php is showing all servers online.
I have prepared my traceroute output, the logfile of my SIP-ATA with the errors (I have also tried with a softphone). Also, as it seems, their fail-ober strategy is not working. I have DNS SRV in my softphone ("Telephone" on OS X), and nothing happened.
Judging by another comment, the US server is offline, too? That might explain the SRV fail.
A traceroute goes till the server. So server is up. This must be something on the software side of the server.