I am assuming you're adding Record-Route to your initial INVITEs?
If so, in the case of the answered call, it might be a defective UA that doesn't follow Record-Route for in-dialog messages (which include e2e ACK).
In the case of the negative replies, a scanner might not waste additional resources sending a formally requisite ACK. It'll just move on to the next target, and leave you holding the bag on the unacknowledged failed transaction.
-- Alex -- Alex Balashov | Principal | Evariste Systems LLC 1447 Peachtree Street NE, Suite 700 Atlanta, GA 30309 United States Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct) Web: http://www.evaristesys.com/, http://www.csrpswitch.com/ _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
