The gateway releasing the call is expecting to see a connect ack message. I’m not sure from teh trace which is teh Clarent and which is the cisco. There is a registry key in the clarent gateway that can be added to always send connect ACK, but I cant quite remember it. Accorsing to Q931 specs connect ACK is not manadatory unless you are in master mode, try swapping over the master clocking role.
Hope this helps,