diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_rewrite.c b/openbsc/src/osmo-bsc_nat/bsc_nat_rewrite.c
index 1eed149..c9b6f4a 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_rewrite.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_rewrite.c
@@ -2,8 +2,8 @@
  * Message rewriting functionality
  */
 /*
- * (C) 2010-2011 by Holger Hans Peter Freyther <zecke@selfish.org>
- * (C) 2010-2011 by On-Waves
+ * (C) 2010-2013 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010-2013 by On-Waves
  * All Rights Reserved
  *
  * This program is free software; you can redistribute it and/or modify
@@ -65,18 +65,27 @@
 	return new_number;
 }
 
-static char *rewrite_non_international(struct bsc_nat *nat, void *ctx, const char *imsi,
+static char *rewrite_isdn_number(struct bsc_nat *nat, void *ctx, const char *imsi,
 				       struct gsm_mncc_number *called)
 {
+	char *number = called->number;
+
 	if (llist_empty(&nat->num_rewr))
 		return NULL;
 
+	/* only ISDN plan */
 	if (called->plan != 1)
 		return NULL;
-	if (called->type == 1)
-		return NULL;
 
-	return match_and_rewrite_number(ctx, called->number,
+	/* international, prepend */
+	if (called->type == 1) {
+		char int_number[sizeof(called->number) + 2];
+		int_number[0] = '+';
+		memcpy(&int_number[1], number, strlen(number) + 1);
+		number = int_number;
+	}
+
+	return match_and_rewrite_number(ctx, number,
 					imsi, &nat->num_rewr);
 }
 
@@ -110,7 +119,7 @@
 			    TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) - 1);
 
 	/* check if it looks international and stop */
-	new_number = rewrite_non_international(nat, msg, imsi, &called);
+	new_number = rewrite_isdn_number(nat, msg, imsi, &called);
 
 	if (!new_number) {
 		LOGP(DNAT, LOGL_DEBUG, "No IMSI match found, returning message.\n");
@@ -150,6 +159,9 @@
 		called.type = 1;
 		strncpy(called.number, new_number + 2, sizeof(called.number));
 	} else {
+		/* rewrite international to unknown */
+		if (called.type == 1)
+			called.type = 0;
 		strncpy(called.number, new_number, sizeof(called.number));
 	}
 	gsm48_encode_called(out, &called);
diff --git a/openbsc/tests/bsc-nat/bsc_data.c b/openbsc/tests/bsc-nat/bsc_data.c
index fe0051a..5a76689 100644
--- a/openbsc/tests/bsc-nat/bsc_data.c
+++ b/openbsc/tests/bsc-nat/bsc_data.c
@@ -229,6 +229,15 @@
 	0x66, 0xf6, 0x15, 0x02, 0x11, 0x01
 };
 
+/* patch the phone number of cc_setup_national_patched */
+static const uint8_t cc_setup_national_patched_patched[] = {
+	0x00, 0x21, 0xfd, 0x06, 0x01, 0x12,
+	0x6d, 0x00, 0x01, 0x1a, 0x01, 0x00, 0x17, 0x03,
+	0x05, 0x04, 0x06, 0x60, 0x04, 0x02, 0x00, 0x05,
+	0x81, 0x5e, 0x07, 0x91, 0x63, 0x71, 0x32, 0x33,
+	0x66, 0xf6, 0x15, 0x02, 0x11, 0x01
+};
+
 static const uint8_t cc_setup_international[] = {
 	0x00, 0x22, 0xfd, 0x06, 0x01, 0x13,
 	0xe7, 0x00, 0x01, 0x1b, 0x01, 0x00, 0x18, 0x03,
@@ -236,3 +245,11 @@
 	0x81, 0x5e, 0x08, 0x81, 0x00, 0x94, 0x71, 0x33,
 	0x63, 0x66, 0x03, 0x15, 0x02, 0x11, 0x01
 };
+
+static const uint8_t cc_setup_national_again[] = {
+	0x00, 0x22, 0xfd, 0x06, 0x01, 0x12, 0x6d, 0x00,
+	0x01, 0x1b, 0x01, 0x00, 0x18, 0x03, 0x05, 0x04,
+	0x06, 0x60, 0x04, 0x02, 0x00, 0x05, 0x81, 0x5e,
+	0x08, 0x81, 0x63, 0x94, 0x71, 0x32, 0x33, 0x66,
+	0xf6, 0x15, 0x02, 0x11, 0x01
+};
diff --git a/openbsc/tests/bsc-nat/bsc_nat_test.c b/openbsc/tests/bsc-nat/bsc_nat_test.c
index c2931f9..6148a37 100644
--- a/openbsc/tests/bsc-nat/bsc_nat_test.c
+++ b/openbsc/tests/bsc-nat/bsc_nat_test.c
@@ -1,8 +1,8 @@
 /*
  * BSC NAT Message filtering
  *
- * (C) 2010-2012 by Holger Hans Peter Freyther <zecke@selfish.org>
- * (C) 2010-2012 by On-Waves
+ * (C) 2010-2013 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010-2013 by On-Waves
  *
  * All Rights Reserved
  *
@@ -985,6 +985,62 @@
 
 	verify_msg(out, cc_setup_national, ARRAY_SIZE(cc_setup_national));
 	msgb_free(out);
+
+	/* Now see what happens to an international number */
+	entry.mnc = "*";
+	entry.option = "^\\+[0-9][0-9]([1-9])";
+	entry.text = "0036";
+	bsc_nat_num_rewr_entry_adapt(nat, &nat->num_rewr, &entries);
+	msg = msgb_alloc(4096, "test_dt_filter");
+	copy_to_msg(msg, cc_setup_national_patched, ARRAY_SIZE(cc_setup_national_patched));
+	parsed = bsc_nat_parse(msg);
+	if (!parsed) {
+		printf("FAIL: Could not parse ID resp %d\n", __LINE__);
+		abort();
+	}
+
+	out = bsc_nat_rewrite_msg(nat, msg, parsed, imsi);
+	if (!out) {
+		printf("FAIL: A new message should be created %d.\n", __LINE__);
+		abort();
+	}
+
+	if (msg == out) {
+		printf("FAIL: The message should have changed %d\n", __LINE__);
+		abort();
+	}
+
+	verify_msg(out, cc_setup_national_patched_patched,
+			ARRAY_SIZE(cc_setup_national_patched_patched));
+	msgb_free(out);
+
+	/* go from international back to national */
+	entry.mnc = "*";
+	entry.option = "^\\+([0-9])";
+	entry.text = "36";
+	bsc_nat_num_rewr_entry_adapt(nat, &nat->num_rewr, &entries);
+	msg = msgb_alloc(4096, "test_dt_filter");
+	copy_to_msg(msg, cc_setup_national_patched, ARRAY_SIZE(cc_setup_national_patched));
+	parsed = bsc_nat_parse(msg);
+	if (!parsed) {
+		printf("FAIL: Could not parse ID resp %d\n", __LINE__);
+		abort();
+	}
+
+	out = bsc_nat_rewrite_msg(nat, msg, parsed, imsi);
+	if (!out) {
+		printf("FAIL: A new message should be created %d.\n", __LINE__);
+		abort();
+	}
+
+	if (msg == out) {
+		printf("FAIL: The message should have changed %d\n", __LINE__);
+		abort();
+	}
+
+	verify_msg(out, cc_setup_national_again,
+			ARRAY_SIZE(cc_setup_national_again));
+	msgb_free(out);
 }
 
 static void test_sms_smsc_rewrite()