We added a 3rd Nameserver to voipo.com - there was an inconsistency in the DNS on the 3rd Nameserver (it was promptly corrected), however if you're still having problems - it's very likely that you cached a bad IP, resulting in 'support.voipo.com' or 'secure.voipo.com' resolving to an older IP.

The fix would be to flush your local DNS cache.
On windows you can do this with "ipconfig /flushdns" in your command prompt window.