[Serusers] Problem with CANCEL and call redirection

Hi all, I'm trying to do a serial call forwarding if callees don't answer. I've added a field in a table which is the number the users want to forward the call if they don't answer. I've a shell script (myScript.sh) which works like that: If the forward mode is activated for the user, then the address is overwritten and the script returns 0, else it returns 1. My main route ends by "t_on_failure("1");" in my ser.cfg, and I've write these lines after the main route: /failure_route[1] { if (exec_dset("/path/to/myscript/myScript.sh \"$SIP_HF_TO\"")); { route(2); } break; } route[2] { sl_send_reply("300","Redirect"); break; } / I also use the tm module and I've set the fr_inv_timer and the fr_timer to the values I wanted. In my configuration : User 1 wants to forward the call to User 2. User 2 wants to forward the call to User 3. User 3 wants to forward the call to User 1. When User 4 calls User 1, who doesn't answer, the call is well forwarded to User 2 after 5 ringings. User 2 doesn't answer and the call is well forwarded to User 3 . Etc. So it works fine, if at least one of the callee answers. But if the caller hangs up (sending a CANCEL to the callee), the phones are always ringing and forwarding the call in the same order. Does anybody have an idea to solve this problem? Thanks. B.R. Xavier.