--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-manual-out/dummy_rtp.c	Tue Sep 20 10:14:18 2022 -0800
@@ -0,0 +1,66 @@
+/*
+ * In this module we implement the code that connects to themwi-mgw
+ * and obtains a dummy PSTN-side RTP endpoint.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include "../include/tmgw_ctrl.h"
+#include "../include/tmgw_const.h"
+
+struct sockaddr_in dummy_rtp_endp;
+
+static char tmgw_socket_pathname[] = "/var/gsm/tmgw_socket";
+
+obtain_dummy_rtp()
+{
+	struct sockaddr_un sa;
+	unsigned sa_len;
+	int fd, rc;
+	struct tmgw_ctrl_req req;
+	struct tmgw_ctrl_resp resp;
+
+	fd = socket(AF_UNIX, SOCK_SEQPACKET, 0);
+	if (fd < 0) {
+		perror("socket(AF_UNIX, SOCK_SEQPACKET, 0)");
+		exit(1);
+	}
+	fill_sockaddr_un(tmgw_socket_pathname, &sa, &sa_len);
+	rc = connect(fd, (struct sockaddr *) &sa, sa_len);
+	if (rc < 0) {
+		perror(tmgw_socket_pathname);
+		exit(1);
+	}
+	bzero(&req, sizeof req);
+	req.opcode = TMGW_CTRL_OP_CRCX;
+	req.ep_id = TMGW_EP_TYPE_DUMMY_PSTN;
+	rc = send(fd, &req, sizeof req, 0);
+	if (rc < 0) {
+		perror("send to TMGW socket");
+		exit(1);
+	}
+	rc = recv(fd, &resp, sizeof resp, 0);
+	if (rc < 0) {
+		perror("recv from TMGW socket");
+		exit(1);
+	}
+	if (rc != sizeof resp) {
+		fprintf(stderr,
+	"error: response packet from TMGW has wrong length (%d bytes)\n",
+			rc);
+		exit(1);
+	}
+	if (resp.res != TMGW_RESP_OK) {
+		fprintf(stderr, "TMGW CRCX returned error %u\n", resp.res);
+		exit(1);
+	}
+	bcopy(&resp.pstn_addr, &dummy_rtp_endp, sizeof(struct sockaddr_in));
+	return(0);
+}