Hi,
Here is a starter link for you
http://www.cisco.com/c/en/us/support/docs/voice-unified-communications/unified-contact-center-express/49820-cad-login-fails-device-assoc.html#error3
You should ask this question in the IP telephony forum
https://supportforums.cisco.com/community/5961/ip-telephony
Regards
Alex
Regards,
Alex.
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