diff --git a/openbsc/tests/bsc-nat/Makefile.am b/openbsc/tests/bsc-nat/Makefile.am
index 0847678..1078d9b 100644
--- a/openbsc/tests/bsc-nat/Makefile.am
+++ b/openbsc/tests/bsc-nat/Makefile.am
@@ -2,7 +2,7 @@
 AM_CFLAGS=-Wall -ggdb3 $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOSCCP_CFLAGS) $(LIBOSMOABIS_CFLAGS) $(COVERAGE_CFLAGS)
 AM_LDFLAGS = $(COVERAGE_LDFLAGS)
 
-EXTRA_DIST = bsc_nat_test.ok bsc_data.c barr.cfg barr_dup.cfg
+EXTRA_DIST = bsc_nat_test.ok bsc_data.c barr.cfg barr_dup.cfg prefixes.csv
 
 noinst_PROGRAMS = bsc_nat_test
 
@@ -12,6 +12,7 @@
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_utils.c \
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_filter.c \
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_rewrite.c \
+			$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_rewrite_trie.c \
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_mgcp_utils.c
 bsc_nat_test_LDADD = $(top_builddir)/src/libbsc/libbsc.a \
 			$(top_srcdir)/src/libctrl/libctrl.a \
diff --git a/openbsc/tests/bsc-nat/bsc_nat_test.c b/openbsc/tests/bsc-nat/bsc_nat_test.c
index 4a244db..b035004 100644
--- a/openbsc/tests/bsc-nat/bsc_nat_test.c
+++ b/openbsc/tests/bsc-nat/bsc_nat_test.c
@@ -26,6 +26,7 @@
 #include <openbsc/gsm_data.h>
 #include <openbsc/bsc_nat.h>
 #include <openbsc/bsc_nat_sccp.h>
+#include <openbsc/nat_rewrite_trie.h>
 
 #include <osmocom/core/application.h>
 #include <osmocom/core/backtrace.h>
@@ -1041,6 +1042,55 @@
 	msgb_free(out);
 }
 
+static void test_setup_rewrite_prefix(void)
+{
+	struct msgb *msg = msgb_alloc(4096, "test_dt_filter");
+	struct msgb *out;
+	struct bsc_nat_parsed *parsed;
+	const char *imsi = "27408000001234";
+
+	struct bsc_nat *nat = bsc_nat_alloc();
+
+	/* a fake list */
+	struct osmo_config_list entries;
+	struct osmo_config_entry entry;
+
+	INIT_LLIST_HEAD(&entries.entry);
+	entry.mcc = "274";
+	entry.mnc = "08";
+	entry.option = "^0([1-9])";
+	entry.text = "prefix_lookup";
+	llist_add_tail(&entry.list, &entries.entry);
+	bsc_nat_num_rewr_entry_adapt(nat, &nat->num_rewr, &entries);
+
+        nat->num_rewr_trie = nat_rewrite_parse(nat, "prefixes.csv");
+
+	msgb_reset(msg);
+	copy_to_msg(msg, cc_setup_national, ARRAY_SIZE(cc_setup_national));
+	parsed = bsc_nat_parse(msg);
+	if (!parsed) {
+		printf("FAIL: Could not parse ID resp\n");
+		abort();
+	}
+
+	out = bsc_nat_rewrite_msg(nat, msg, parsed, imsi);
+	if (!out) {
+		printf("FAIL: A new message should be created.\n");
+		abort();
+	}
+
+	if (msg == out) {
+		printf("FAIL: The message should have changed\n");
+		abort();
+	}
+
+	verify_msg(out, cc_setup_national_patched, ARRAY_SIZE(cc_setup_national_patched));
+	msgb_free(out);
+
+	bsc_nat_num_rewr_entry_adapt(nat, &nat->num_rewr, NULL);
+	talloc_free(nat);
+}
+
 static void test_sms_smsc_rewrite()
 {
 	struct msgb *msg = msgb_alloc(4096, "SMSC rewrite"), *out;
@@ -1322,6 +1372,7 @@
 	test_cr_filter();
 	test_dt_filter();
 	test_setup_rewrite();
+	test_setup_rewrite_prefix();
 	test_sms_smsc_rewrite();
 	test_sms_number_rewrite();
 	test_mgcp_allocations();
diff --git a/openbsc/tests/bsc-nat/prefixes.csv b/openbsc/tests/bsc-nat/prefixes.csv
new file mode 100644
index 0000000..0b66ffe
--- /dev/null
+++ b/openbsc/tests/bsc-nat/prefixes.csv
@@ -0,0 +1 @@
+0172,0049
diff --git a/openbsc/tests/testsuite.at b/openbsc/tests/testsuite.at
index 148b3d3..e54d4b5 100644
--- a/openbsc/tests/testsuite.at
+++ b/openbsc/tests/testsuite.at
@@ -34,6 +34,7 @@
 AT_SETUP([bsc-nat])
 AT_KEYWORDS([bsc-nat])
 AT_CHECK([test "$enable_nat_test" != no || exit 77])
+cp $abs_srcdir/bsc-nat/prefixes.csv .
 cp $abs_srcdir/bsc-nat/barr.cfg .
 cp $abs_srcdir/bsc-nat/barr_dup.cfg .
 cat $abs_srcdir/bsc-nat/bsc_nat_test.ok > expout
diff --git a/openbsc/tests/vty_test_runner.py b/openbsc/tests/vty_test_runner.py
index 456573d..91b4684 100644
--- a/openbsc/tests/vty_test_runner.py
+++ b/openbsc/tests/vty_test_runner.py
@@ -103,6 +103,27 @@
         res = self.vty.command("number-rewrite rewrite.cfg")
         res = self.vty.command("no number-rewrite")
 
+    def testPrefixTreeLoading(self):
+        cfg = os.path.join(confpath, "tests/bsc-nat-trie/prefixes.csv")
+
+        self.vty.enable()
+        self.vty.command("configure terminal")
+        self.vty.command("nat")
+        res = self.vty.command("prefix-tree %s" % cfg)
+        self.assertEqual(res, "% prefix-tree loaded 17 rules.")
+        self.vty.command("end")
+
+        res = self.vty.command("show prefix-tree")
+        self.assertEqual(res, '1,1\r\n12,2\r\n123,3\r\n1234,4\r\n12345,5\r\n123456,6\r\n1234567,7\r\n12345678,8\r\n123456789,9\r\n1234567890,10\r\n13,11\r\n14,12\r\n15,13\r\n16,14\r\n82,16\r\n823455,15\r\n+49123,17')
+
+        self.vty.command("configure terminal")
+        self.vty.command("nat")
+        self.vty.command("no prefix-tree")
+        self.vty.command("end")
+
+        res = self.vty.command("show prefix-tree")
+        self.assertEqual(res, "% there is now prefix tree loaded.")
+
 
 def add_nat_test(suite, workdir):
     if not os.path.isfile(os.path.join(workdir, "src/osmo-bsc_nat/osmo-bsc_nat")):