Issues with SPI & DPI Sip Re-registration

I have a couple clients that I have noticed re-register over and over again, I found that one of them is using a Cisco ASA with Deep Packet Inspection on and seems to be the issue. That particular client had no issue with turning it off and the issue completely went away. Has anyone else had this issue and are there other ways to resolve it. My next client did not want to disable it.