--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-out/retrans.c	Tue Oct 11 23:04:01 2022 -0800
@@ -0,0 +1,74 @@
+/*
+ * In this module we handle retransmission of our outgoing SIP UAC packets.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <syslog.h>
+#include "../include/gsm48_const.h"
+#include "../include/out_routes.h"
+#include "../libsip/out_msg.h"
+#include "call.h"
+
+extern unsigned cfg_retrans_count;
+extern unsigned sip_linger_timeout;
+extern unsigned sip_linger_bye_out_err;
+extern struct call *call_list;
+
+void
+run_periodic_retrans()
+{
+	struct call *call;
+	struct sip_msg_out msg;
+
+	for (call = call_list; call; call = call->next) {
+		switch (call->sip_state) {
+		case SIP_STATE_INV_SENT:
+			if (call->sip_tx_count < cfg_retrans_count) {
+				fill_invite_req_msg(&msg, call);
+				sip_tx_packet(&msg, &call->udp_sin);
+				call->sip_tx_count++;
+			} else {
+				syslog(LOG_ERR,
+					"outbound INVITE retrans timeout");
+				call->overall_state = OVERALL_STATE_TEARDOWN;
+				disconnect_mncc(call, GSM48_CAUSE_LOC_PRN_S_LU,
+						GSM48_CC_CAUSE_DEST_OOO);
+				disconnect_tmgw(call);
+				call->sip_state = SIP_STATE_ACCEPT_100;
+				sip_mark_end_time(call, sip_linger_timeout);
+			}
+			break;
+		case SIP_STATE_CANCEL_SENT:
+			if (call->sip_tx_count < cfg_retrans_count) {
+				fill_cancel_req_msg(&msg, call);
+				sip_tx_packet(&msg, &call->udp_sin);
+				call->sip_tx_count++;
+			} else {
+				syslog(LOG_ERR,
+					"outbound CANCEL retrans timeout");
+				call->sip_state = SIP_STATE_ACCEPT_200;
+				sip_mark_end_time(call, sip_linger_timeout);
+			}
+			break;
+		case SIP_STATE_BYE_SENT:
+			if (call->sip_tx_count < cfg_retrans_count) {
+				fill_bye_req_msg(&msg, call);
+				sip_tx_packet(&msg, &call->udp_sin);
+				call->sip_tx_count++;
+			} else {
+				syslog(LOG_ERR, "outbound BYE retrans timeout");
+				call->sip_state = SIP_STATE_ENDED;
+				sip_mark_end_time(call, sip_linger_bye_out_err);
+			}
+			break;
+		}
+	}
+}