[Serusers] ACKs not getting routed?

I am having a problem with incoming calls where ACK messages don’t seem to be getting (loose) routed. Here is the relevant part of my config ====================== route {         xlog("L_ERR", "time [%Tf] method <%rm> r-uri <%ru> - %tu\n");         # initial sanity checks -- messages with         # max_forwards==0, or excessively long requests         if (!mf_process_maxfwd_header("10")) {                 sl_send_reply("483","Too Many Hops -- probebly a loop or something");                 break;         };         if ( msg:len > max_len ) {                 sl_send_reply("513", "Message too big");                 break;         };         # we record-route all messages -- to make sure that         # subsequent messages will go through our proxy for accounting purposes         record_route();         #Accounting if a call is started or ended         if (method=="INVITE" || method=="BYE" || method=="CANCEL") {                 acc_rad_request("200");         }         # grant Route routing if route headers present         # loose-route processing. Decreases security slightly regarding         # forged messages, but decreases load.         if (loose_route()) {                 xlog("L_NOTICE", "Loose Routing\n");                 t_relay();                 break;         }; ====================== My understand is this should cause the ACK messages that are part of the transaction to get routed. They should not pass beyond this block of code right? However, the SIP conversation goes as follows. Gateway invites proxy Proxy says 100 trying Proxy says 100 trying Proxy invites user User says 100 trying User says 180 Ringing User says 180 Ringing Thus far all is well When the user picks up the phone User tells proxy 200 ok Proxy tells gateway 200 ok Gateway tells proxy ACK At this point the proxy should be relaying the ACK to the user, but it does not. Instead due to timeout the user sends another 200 ok and that last block of conversation repeats. Any ideas why this would not be working? (I tried to send this with a full SIP dialog but it got rejected as being too big so this email is the chopped down version)