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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hi,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am using Kamailio as a gateway for inbound calls to a group of Asterisk servers.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>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.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I thought of t_suspend/t_continue functionality in Kamailio. I have implemented this:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>CallA arrives.<o:p></o:p></p><p class=MsoNormal>Send 180-ringing<o:p></o:p></p><p class=MsoNormal>Use ds_select_dst() to choose an Asterisk to handle the paired calls<o:p></o:p></p><p class=MsoNormal>Store destination and other data in an htable so that I can match the call later.<o:p></o:p></p><p class=MsoNormal>Invoke t_suspend() for CallA.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>What I have implemented when the matching call arrives is this:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>CallB arrives (and some logic matches it to the suspended CallA).<o:p></o:p></p><p class=MsoNormal>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.<o:p></o:p></p><p class=MsoNormal>Set $du on CallB to match the destination, then t_relay() this call to send it on to the same Asterisk.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The solution almost works, but there is a problem.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The t_relay() for CallA is fine, and the call is forwarded.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>When the script runs the t_relay() for CallB, I get this logged:<br>ERROR: tm [t_fwd.c:1728]: t_forward_nonack(): no branches for forwarding<o:p></o:p></p><p class=MsoNormal>ERROR: sl [sl_funcs.c:362]: sl_reply_error(): stateless error reply used: I'm terribly sorry, server error occurred (6/SL)<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>AND after each call I notice an extra transaction stuck in Kamailio (when I use kamctl rpc tm.list).<o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>Can anyone point out where my Kamailio/SIP understanding has let me down? <o:p></o:p></p><p class=MsoNormal>Many Thanks,<o:p></o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-GB'>Mark Hall<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>