[Users] statefull handling of 6xx responses

RFC 3261 defines that upon reception of a 6xx response, a proxy SHOULD cancel all forked dialogs and send back the 6xx as the final response to the upstream UA. --- rfc 3261, section 16.7 ------- Under the new rules, upon receiving a 6xx, a proxy will issue a CANCEL request, which will generally result in 487 responses from all outstanding client transactions, and then at that point the 6xx is forwarded upstream. ---------------------------------- Some call forking experiments have shown that openser 1.2 does not follow these rules, instead it seems to disregard any 6xx response and continue with normal processing of existing forked dialogs. E.g. if a call forks to five phones and one of them sends back a 603 Declined response, the other four phones continue to ring until fr_inv_timer fires and failure_route is called with a status of 408 Timeout. Is it possible to make openser more SIP RFC compliant through configuration or does this need a code change? thanks, Christian