we have an office communicator server in our office that use for Instant messaging. It has been working well, but this afternoon people couldn't sign on.
I checked the event viewer and found this warning:
Could not establish application endpoint with OCS on company.fully.qualified.domain.name:5061
Exception: Microsoft.Rtc.Signaling.RegisterException - 504 - The endpoint was unable to register. See the ErrorCode for specific reason.
Inner Exception: ~
The service will retry every 30 seconds.
I tried to search for reference online, but couldn't find much. Can anyone please help on explaining what might have caused this error message? thank you very much.