While searching for the above specified error i have come to many sites that describe the same problem and suggest many solutions.Here in this post i will try to publish what was the solution that works for me.
in my very specific situation the error was originating from user that his sip address was in a domain different than the domain we installed office communicator pool on it but in a domain that is trusted by the OCS server domain.
when i started the troubleshooting i took a look at the event viewer on the OCS server and discovered that there was alot of information with event ID “User Replicator connected to domain controller dc1.contoso.com in domain contoso.com to perform synchronization” and when i tried to enable a user for OCS communication in the contoso.com domain it didn’t work. Further troubleshooting leads me to open the resource database table in the “RTC” database and query the users in the tables to see if the user gets created, here also the results was negative. After some researches i tried to re-prepare the domain contoso.com for the OCS server by using the command “LCSCmd.exe /Domain:contoso.com /Action:DomainPrep” and then recheck the status by using the command “LCSCmd.exe /Domain:contoso.com /Action:CheckDomainPrepState” after initiating this command the users got created immediately in the OCS database and the problem was resolved.