[Users] rewritehost failure route

Hello, I 've problem with rewritehost function in failure_route with openser 1.1.0 In core functions i don't know in which route can i use them, unlike functions in modules. I 'd like to make a failover system, In route block rewritehost is successfull but on failure route there is no effect i think, i pass the host to t_relay, so it is relayed to correct host, but in r-uri, there is incorrect host, and sip proxy reply with (SIP/2.0 400 Bad Request - 'Invalid IP Address) route{ ...... t_on_failure("1"); rewritehost("xxx.xxx.xxx.90"); t_relay(); ..... } failure_route[1] { t_on_failure("2"); append_branch(); rewritehost("xxx.xxx.xxx.91"); t_relay("xxx.xxx.xxx.91"); } failure_route[2] { # failover cisco (zajcek) append_branch(); rewritehost("xxx.xxx.xxx.31"); t_relay("xxx.xxx.xxx.31"); } Thanks any help, Tamas