Hi John,
This problem can be seen due to the multiple issue but most commonly it has been notice when you have codec mismatch or any share line appearence since CTI ports and CTI route point has to be the uniquie DN's and also CUxAC only support G711 due to the tsp limitation..
Verify if it is happening only with the internal call or external calls..If the problem reoccur try to capture the following detail logs to find the root cause of the issue..
Call manager trace
CTI manager traces
TSP traces
Make sure to note the calling party and call party number and the operator extension..
I hope this help
Thanks
Shahrukh Qureshi