[Serusers] Removing to-tags

Hi All Is there a way/hack to remove to-tags from incoming '180 Ringing' responses before forwarding them to the UAC. My reason for doing this is that one of the UACs I am using seems to screw the to-tag up when SER acts as a forking proxy. i.e. the calling UA sends an ACK for the 200OK with the to-tag equal to the to-tag received from the FIRST '180 RINGING' received. The net result is that the ACK is sent with a different to-tag than the to-tag of the received 200 OK. The answering UA therefore does not accept the ACK and the call is not completed. Any help/guidance would be much appreciated Jason Penton Rhodes University Grahamstown South Africa