Hi Benny, I'm a bit confused about the setting of regc->current_op in the tsx_callback function of sip_reg.c. As far as I can see there are 4 branches and regc->current_op gets set to REGC_IDLE in 3 out of those 4. Now for some reason I am getting a non-auth related 4xx reply from my sip proxy on registration, which leaves the current_op attribute set to REGC_REGISTERING. Now when I try to resend my registration, I get an assertion failure. It seems to be regc->current_op could just be set to REGC_IDLE whenever tsx_callback is called, or is this some grave mistake? Ruud Klaver AG Projects