Hi,
Please follow this guide as this should help you.
http://www.akuvox.com/upload/file/201507241437725669682511.pdf
Use push button feature from above doc to initiate call to CUCM pilot number.
For registration process make sure you have configured sip accounts in your device.
I have never tried this, however advanced sip profile for third party should help you and make sure the transport is UDP on both sides.
Regards,
Raaj