[Users] timeout for serial forking

Hi Users, I have a problem with timeout for serial forking: I want to deviate a certain type of call to Voicemail after 19 seconds, then i do: ... modparam("tm", "fr_inv_timer_avp", "fr_inv_timeout") ... if (uri=~"^sip:xyz") { # set timeout for VoiceMail avp_write("i:19", "fr_inv_timeout"); t_on_failure("1"); }; ... if (!t_relay()) { sl_reply_error(); }; ... failure_route[1] { # send it to VM rewritehostport("xxx.xxx.xxx.xxx:5060"); forward(uri:host, uri:port); } when the timer hits, OpenSER sends a new INVITE to VoiceMail and a 408 Request Timeout to the calling UA. this cause the calling UA (X-Lite) to hang up. is it my bad implementation or is it a problem of X-Lite? same configuration works when I call with an ALLNET Phone... thanks for your interest, Stefano