Run a sniffer (wireshark) between HP4K and Cisco CUCM.
By analyzing the sniffer it is possible to find out where the lock comes from.
Configuration example:
ADD-GKREG:6,EXTGW®GW&HG3550V2&SIP,10.100.16.231,8,0,0,1,"CUCM_PCAM",TRADITIO;
ADD-WABE:0025,,,NETRTE,N...