[SR-Users] Try backup route

I'm using Kamailio 3.1 I have a custom routing statement called MYROUTE which is placed like this: route {  ...  route (MYROUTE);  route (RELAY);} Inside MYROUTE I do some custom SQL checking that basically selects the least cost provider for the ongoing call. The MYROUTE routine sets the $rU, $rd and $rp variables in case a provider has been found for the dialed number or fails with Sip code 404. All this works perfectly, except in my database I also have an alternate provider that I only wish to use as backup in case the main provider returns a 5XX code. How do I get Kamailio to try the second provider after the first one failed ? So far I've tried setting up a t_on_failure() command & routine that picks up the backup provider from the database and sets $rU, $rd margin-right:0px;margin-bottom:0px;margin-left:0px;padding-top:0px;padding-right:0px;padding-bottom:0px;padding-left:0px;">   0(11460) DEBUG: [parser/msg_parser.c:167]: get_hdr_field: cseq :   0(11460) DEBUG: [parser/msg_parser.c:201]: DEBUG: get_hdr_body : content_length=0  0(11460) DEBUG: [parser/msg_parser.c:103]: found end of header  0(11460) DEBUG: maxfwd [mf_funcs.c:66]: max_forwards header not found!  0(11460) DEBUG: [parser/parse_to.c:174]: DEBUG: add_param: tag=4a2aab60  0(11460) DEBUG: [parser/parse_to.c:803]: end of header reached, state=29  0(11460) DEBUG: siputils [checks.c:76]: totag found  0(11460) DEBUG: rr [loose.c:108]: No Route headers found  0(11460) DEBUG: rr [loose.c:910]: There is no Route HF I believe the problem is that t_on_failure() does not keep all the proper data associated with the call and that's why it fails. Maybe t_on_failure isn't the right command to use here after all (?). So to resume. Here's what I wish to achieve: 1 Call comes through2. Goes through MYROUTE where a provider is selected3. Call is attempted through provider found in #24. If call fails , select another provider5. Call is attempted through provider found in #4 Thanks!