--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-in/call_setup.c	Sat Sep 17 18:43:08 2022 -0800
@@ -0,0 +1,70 @@
+/*
+ * In this module we implement incoming call setup toward GSM.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.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/mncc.h"
+#include "../include/gsm48_const.h"
+#include "call.h"
+
+static void
+fill_calling_number(from, caller)
+	char *from;
+	struct gsm_mncc_number *caller;
+{
+	char *num;
+	int cc;
+
+	if (!strcasecmp(from, "Restricted")) {
+		caller->present = GSM48_PRES_RESTR;
+		return;
+	}
+	if (*from == '+')
+		num = from + 1;
+	else
+		num = from;
+	cc = grok_number_string(num, 0);
+	if (cc < 1 || cc > 32) {
+		/* not a valid number */
+		caller->present = GSM48_PRES_UNAVAIL;
+		return;
+	}
+	/* accept "From" user as a valid number */
+	strcpy(caller->number, num);
+	caller->plan = GSM48_NPI_ISDN_E164;
+	if (*from == '+')
+		caller->type = GSM48_TON_INTERNATIONAL;
+}
+
+void
+proceed_with_call_setup(call)
+	struct call *call;
+{
+	struct gsm_mncc setup_msg;
+
+	allocate_mncc_callref(call);
+	bzero(&setup_msg, sizeof setup_msg);
+	setup_msg.msg_type = MNCC_SETUP_REQ;
+	setup_msg.callref = call->mncc_callref;
+	/* fill called number */
+	setup_msg.called.type = GSM48_TON_INTERNATIONAL;
+	setup_msg.called.plan = GSM48_NPI_ISDN_E164;
+	setup_msg.called.number[0] = '1';
+	strcpy(setup_msg.called.number+1, call->called_nanp);
+	setup_msg.fields |= MNCC_F_CALLED;
+	/* fill calling number */
+	call->from_user[call->from_user_len] = '\0';
+	fill_calling_number(call->from_user, &setup_msg.calling);
+	call->from_user[call->from_user_len] = '@';
+	setup_msg.fields |= MNCC_F_CALLING;
+	send_mncc_to_gsm(&setup_msg, sizeof(struct gsm_mncc));
+	call->overall_state = OVERALL_STATE_CALL_GSM;
+}