If the setting below are Ok then please check if the port TCP 2748 is open, otherwise please send us a PRT.
1) The Phone is under the End User control (End User confug page > controlled devices)
2) The End User has the User Group/Role Standard CTI Enabled.
3) The End User is licenses for CUPC.
4) A CTI Profile and a CCMIP Profiles have been assigned to the User on CUPS.
5) If EM is used try without it first.
Regards,
-Fabricio MS