Also, it doesn't seem to me that this can be accomplished with the RFC-defined T-timers.
Alex Balashov wrote:
It would be really nice to have a feature in TM for even faster failover that is turned off when any reply is received at all, provisional or otherwise.
The problem with fr_timer and fr_inv_timer is that they throw on lack of final reply. But sometimes gateways have very lengthy, complicated asynchronous operations that must complete before they can return a final OK. If you are doing failover, the most important thing to know is that the gateway is there at all, which the provisional 1xx message accomplishes.
What would be really nice is to have a timer that can be diffused as soon as a provisional reply arrives.
I don't see how this can be accomplished with any of the existing timers.