k, thank you for your quick response 

Hey All, did you find any solution for this? I also ran into this problem today with CUCM 11.5 cluster and 8841 phones. I then checked another CUCM 14 cluster and 8841 phones with the same problem.... Thank you 

@GirijeshKumar your solution helped me too =))

Hi,on which CUCM version did you try it?I got errors with CUCM 10.5(2)SU2a (always got error message: "Error in Authentication"). With CUCM 11.5(1)SU1 everythig worked fine.Regards,Sven