I have the same problems with my extensions. It happened after something went wrong with WWW3.pbxes and the account was moved to WWW4.pbxes. Think it happened around noon European time, and the problem still exists at 3.40 in the morning, that is more than 15 hours!!!
The www3 server is not accessible from the Internet, and this issue has been going on for the last 4 days. Move your account to another server if you can, to restore service temporarily.
I am well aware this might not be a solution for a lot of people, so there is no need for rehashing it.