Hi Joel, I have resolved the issue now, it was a problem with my original code. There was a rogue ‘exit’, which was causing one transaction to be left unmanaged. I did think of Tsilo initially (after looking at Federico’s 2015 presentation) but it doesn’t quite match my scenario. Many Thanks, Mark From: sr-users [mailto:sr-users-bounces@lists.kamailio.org] On Behalf Of Joel Serrano Sent: 08 February 2019 03:08 To: Kamailio (SER) - Users Mailing List Subject: Re: [SR-Users] Waiting for calls Hello Mark, Have you given TSILO module a try? https://kamailio.org/docs/modules/5.2.x/modules/tsilo.html On Thu, Feb 7, 2019 at 12:18 Mark Hall &lt;mark(a)brightvoip.co.uk <mailto:mark@brightvoip.co.uk> > wrote: Hi, I am using Kamailio as a gateway for inbound calls to a group of Asterisk servers. One particular call scenario involves matching pairs of calls. Originally I was just sending the calls through to Asterisk for processing (including the ‘matching up’), but there is a further requirement that the first received call must not be answered until its matching call arrives – and this is a little awkward in Asterisk, especially if there will be many calls. I thought of t_suspend/t_continue functionality in Kamailio. I have implemented this: CallA arrives. Send 180-ringing Use ds_select_dst() to choose an Asterisk to handle the paired calls Store destination and other data in an htable so that I can match the call later. Invoke t_suspend() for CallA. What I have implemented when the matching call arrives is this: CallB arrives (and some logic matches it to the suspended CallA). Invoke t_continue(‘id’,’label’,’CONTINUE_CALL’); so that CallA is now released and the route ends in t_relay() to send it on to Asterisk. Set $du on CallB to match the destination, then t_relay() this call to send it on to the same Asterisk. The solution almost works, but there is a problem. The t_relay() for CallA is fine, and the call is forwarded. When the script runs the t_relay() for CallB, I get this logged: ERROR: tm [t_fwd.c:1728]: t_forward_nonack(): no branches for forwarding ERROR: sl [sl_funcs.c:362]: sl_reply_error(): stateless error reply used: I'm terribly sorry, server error occurred (6/SL) AND after each call I notice an extra transaction stuck in Kamailio (when I use kamctl rpc tm.list). Can anyone point out where my Kamailio/SIP understanding has let me down? Many Thanks, Mark Hall _______________________________________________ Kamailio (SER) - Users Mailing List sr-users(a)lists.kamailio.org <mailto:sr-users@lists.kamailio.org> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users