diff --git a/configure.ac b/configure.ac
index de760fd..dd2b04a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -44,4 +44,5 @@ AC_OUTPUT(
     tests/Makefile
     tests/mtp/Makefile
     tests/patching/Makefile
+    tests/isup/Makefile
     Makefile)
diff --git a/contrib/TestSender.st b/contrib/TestSender.st
index 4913416..d32348f 100644
--- a/contrib/TestSender.st
+++ b/contrib/TestSender.st
@@ -34,4 +34,9 @@ Eval [
     msg := #(2 0 0 1 0 0 0 0 0 0 0 6 192 232 197 7 0 23) asByteArray.
     datagram data: msg.
     socket nextPut: datagram.
+
+    "ISUP GSR"
+    msg := #(2 0 0 1 0 0 0 0 0 0 0 11 197 8 197 7 224 3 0 23 1 1 28) asByteArray.
+    datagram data: msg.
+    socket nextPut: datagram.
 ]
diff --git a/include/isup_types.h b/include/isup_types.h
new file mode 100644
index 0000000..51c5e79
--- /dev/null
+++ b/include/isup_types.h
@@ -0,0 +1,49 @@
+/*
+ * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef isup_types_h
+#define isup_types_h
+
+#include <stdint.h>
+
+struct msgb;
+struct mtp_link;
+
+/* This is from Table 4/Q.763 */
+#define ISUP_MSG_GRS	0x17
+#define ISUP_MSG_GRA	0x29
+
+struct isup_msg_hdr {
+	uint16_t cic   : 12,
+		 spare :  4;
+	uint8_t  msg_type;
+	uint8_t  data[0];
+} __attribute__((packed));
+
+struct isup_msg_grs {
+	uint8_t  pointer_int;
+};
+
+int mtp_link_forward_isup(struct mtp_link *link, struct msgb *msg, int sls);
+
+int isup_parse_grs(const uint8_t *data, uint8_t length);
+
+#endif
diff --git a/tests/Makefile.am b/tests/Makefile.am
index b38aa6a..6ffa86d 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1 +1 @@
-SUBDIRS = mtp patching
+SUBDIRS = mtp patching isup
diff --git a/tests/isup/Makefile.am b/tests/isup/Makefile.am
new file mode 100644
index 0000000..4c51d25
--- /dev/null
+++ b/tests/isup/Makefile.am
@@ -0,0 +1,4 @@
+INCLUDES = $(all_includes) -I$(top_srcdir)/include -Wall
+noinst_PROGRAMS = isup_parse_test
+
+isup_parse_test_SOURCES = isup_parse_test.c
diff --git a/tests/isup/isup_parse_test.c b/tests/isup/isup_parse_test.c
new file mode 100644
index 0000000..8f99cdb
--- /dev/null
+++ b/tests/isup/isup_parse_test.c
@@ -0,0 +1,48 @@
+/*
+ * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <isup_types.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#define ASSERT(got,want) \
+	if (got != want) { \
+		fprintf(stderr, "Values should be the same 0x%x 0x%x at %s:%d\n", \
+			got, want, __FILE__, __LINE__); \
+		abort(); \
+	}
+
+static void test_cic_parsing()
+{
+	static const uint8_t isup_grs[] = {3, 0, 23, 1, 1, 28};
+	struct isup_msg_hdr *hdr;
+
+	hdr = (struct isup_msg_hdr *) isup_grs;
+	ASSERT(hdr->cic, 3);
+	ASSERT(hdr->msg_type, ISUP_MSG_GRS);
+}
+
+int main(int argc, char **argv)
+{
+	test_cic_parsing();
+	return 0;
+}