CUEAC supports a max of 50 CTI connections to CUCM.you can configure more than 50, but CUCM can only registred the top 50.

The Cisco AXL Web Service must be activated.The JTAPI user need to be associated with the "Standard CTI Enabled" group.Configure a value for "Digest Credentials" for the user in question.

Try to disable the 'Power Save' mode in the hidden menu : http://www.cisco.com/en/US/partner/products/hw/phones/ps379/products_implementation_design_guide_chapter09186a00802a09d6.html

You should add a 'Third-party SIP device(Basic)' associated with a defined digest user.On your Nokia select Nokia 3GPP as service mode in your SIP configuration.

I use the same IOS with MGCP and E1in France, and all is working fine. Here's the configuration :ccm-manager redundant-host X.X.X.Xccm-manager mgcpccm-manager music-on-holdccm-manager config server X.X.X.X!controller E1 2/0 framing NO-CRC4 pri-group ...