You might be looking for PRACK. That resends the 18x until an ACK for it is received, thereby ensuring its delivered. There is a sofia profile parameter that enables it, but it used to have warnings that it was unstable.
You could also use the tcp transport, which would guarantee the 180 was received.
Steve on iPhone
I’d like to be able to make 180 RINGING messages be repeated to the caller every X seconds until the 200 OK (or other error). I dug through the source & FreeSWITCH book but didn’t see a mechanism for doing this. Does FS have such a thing?
Thanks
Kevin