[Users] timeout for serial forking

[Stefano Capitanio]

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