diff --git a/openbsc/include/openbsc/bsc_nat.h b/openbsc/include/openbsc/bsc_nat.h
index bdea434..638791a 100644
--- a/openbsc/include/openbsc/bsc_nat.h
+++ b/openbsc/include/openbsc/bsc_nat.h
@@ -103,6 +103,10 @@
 	struct sccp_source_reference real_ref;
 	struct sccp_source_reference patched_ref;
 	struct sccp_source_reference remote_ref;
+
+	/* GSM audio handling. That is 32 * multiplex + ts */
+	int msc_timeslot;
+	int bsc_timeslot;
 };
 
 /**
@@ -162,4 +166,10 @@
 struct sccp_connections *patch_sccp_src_ref_to_bsc(struct msgb *, struct bsc_nat_parsed *, struct bsc_nat *);
 struct sccp_connections *patch_sccp_src_ref_to_msc(struct msgb *, struct bsc_nat_parsed *, struct bsc_nat *);
 
+/**
+ * MGCP/Audio handling
+ */
+int bsc_mgcp_assign(struct sccp_connections *, struct msgb *msg);
+void bsc_mgcp_clear(struct sccp_connections *);
+
 #endif
diff --git a/openbsc/src/nat/bsc_mgcp_utils.c b/openbsc/src/nat/bsc_mgcp_utils.c
new file mode 100644
index 0000000..55dad38
--- /dev/null
+++ b/openbsc/src/nat/bsc_mgcp_utils.c
@@ -0,0 +1,66 @@
+/*
+ * (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 <openbsc/bsc_nat.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/bssap.h>
+#include <openbsc/debug.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+int bsc_mgcp_assign(struct sccp_connections *con, struct msgb *msg)
+{
+	struct tlv_parsed tp;
+	u_int16_t cic;
+	u_int8_t timeslot;
+	u_int8_t multiplex;
+
+	if (!msg->l3h) {
+		LOGP(DNAT, LOGL_ERROR, "Assignment message should have l3h pointer.\n");
+		return -1;
+	}
+
+	if (msgb_l3len(msg) < 3) {
+		LOGP(DNAT, LOGL_ERROR, "Assignment message has not enough space for GSM0808.\n");
+		return -1;
+	}
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 3, msgb_l3len(msg) - 3, 0, 0);
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)) {
+		LOGP(DNAT, LOGL_ERROR, "Circuit identity code not found in assignment message.\n");
+		return -1;
+	}
+
+	cic = ntohs(*(u_int16_t *)TLVP_VAL(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE));
+	timeslot = cic & 0x1f;
+	multiplex = (cic & ~0x1f) >> 5;
+
+	con->msc_timeslot = (32 * multiplex) + timeslot;
+	con->bsc_timeslot = con->msc_timeslot;
+	return 0;
+}
+
+void bsc_mgcp_clear(struct sccp_connections *con)
+{
+	con->msc_timeslot = -1;
+	con->bsc_timeslot = -1;
+}
diff --git a/openbsc/src/nat/bsc_nat.c b/openbsc/src/nat/bsc_nat.c
index c7c6c41..1568230 100644
--- a/openbsc/src/nat/bsc_nat.c
+++ b/openbsc/src/nat/bsc_nat.c
@@ -193,6 +193,13 @@
 		case SCCP_MSG_TYPE_CREF:
 		case SCCP_MSG_TYPE_DT1:
 			con = patch_sccp_src_ref_to_bsc(msg, parsed, nat);
+			if (parsed->gsm_type == BSS_MAP_MSG_ASSIGMENT_RQST) {
+				if (con) {
+					if (bsc_mgcp_assign(con, msg) != 0)
+						LOGP(DNAT, LOGL_ERROR, "Failed to assign...\n");
+				} else
+					LOGP(DNAT, LOGL_ERROR, "Assignment command but no BSC.\n");
+			}
 			break;
 		case SCCP_MSG_TYPE_CC:
 			con = patch_sccp_src_ref_to_bsc(msg, parsed, nat);
@@ -401,7 +408,10 @@
 			break;
 		case SCCP_MSG_TYPE_RLC:
 			con = patch_sccp_src_ref_to_msc(msg, parsed, nat);
-			remove_sccp_src_ref(bsc, msg, parsed);
+			if (con) {
+				remove_sccp_src_ref(bsc, msg, parsed);
+				bsc_mgcp_clear(con);
+			}
 			break;
 		case SCCP_MSG_TYPE_UDT:
 			/* simply forward everything */
diff --git a/openbsc/src/nat/bsc_nat_utils.c b/openbsc/src/nat/bsc_nat_utils.c
index 3e44193..f1bb4b5 100644
--- a/openbsc/src/nat/bsc_nat_utils.c
+++ b/openbsc/src/nat/bsc_nat_utils.c
@@ -79,6 +79,7 @@
 	LOGP(DNAT, LOGL_DEBUG, "Destroy 0x%x <-> 0x%x mapping for con %p\n",
 	     sccp_src_ref_to_int(&conn->real_ref),
 	     sccp_src_ref_to_int(&conn->patched_ref), conn->bsc);
+	bsc_mgcp_clear(conn);
 	llist_del(&conn->list_entry);
 	talloc_free(conn);
 }
diff --git a/openbsc/tests/bsc-nat/Makefile.am b/openbsc/tests/bsc-nat/Makefile.am
index d26bbeb..bcd9f18 100644
--- a/openbsc/tests/bsc-nat/Makefile.am
+++ b/openbsc/tests/bsc-nat/Makefile.am
@@ -9,5 +9,6 @@
 			$(top_srcdir)/src/nat/bsc_filter.c \
 			$(top_srcdir)/src/nat/bsc_sccp.c \
 			$(top_srcdir)/src/nat/bsc_nat_utils.c \
+			$(top_srcdir)/src/nat/bsc_mgcp_utils.c \
 			$(top_srcdir)/src/bssap.c
 bsc_nat_test_LDADD = $(top_builddir)/src/libbsc.a $(top_builddir)/src/libsccp.a $(LIBOSMOCORE_LIBS)
diff --git a/openbsc/tests/bsc-nat/bsc_data.c b/openbsc/tests/bsc-nat/bsc_data.c
index b73aff1..ca170e2 100644
--- a/openbsc/tests/bsc-nat/bsc_data.c
+++ b/openbsc/tests/bsc-nat/bsc_data.c
@@ -80,3 +80,10 @@
 0x10, 0x52, 0x08, 0x08, 0x29, 0x47, 0x10, 0x02,
 0x01, 0x50, 0x02, 0x30, 0x1a, 0x03, 0x05, 0x20,
 0x15 };
+
+/* an assignment command */
+static const u_int8_t ass_cmd[] = {
+0x00, 0x12, 0xfd, 0x06,
+0x00, 0x00, 0x49, 0x00, 0x01, 0x0b, 0x00, 0x09,
+0x01, 0x0b, 0x03, 0x01, 0x0a, 0x11, 0x01, 0x00,
+0x15 };
diff --git a/openbsc/tests/bsc-nat/bsc_nat_test.c b/openbsc/tests/bsc-nat/bsc_nat_test.c
index 3a10960..70e98d7 100644
--- a/openbsc/tests/bsc-nat/bsc_nat_test.c
+++ b/openbsc/tests/bsc-nat/bsc_nat_test.c
@@ -335,6 +335,41 @@
 	talloc_free(parsed);
 }
 
+static void test_mgcp(void)
+{
+	struct sccp_connections con;
+	struct bsc_nat_parsed *parsed;
+	struct msgb *msg;
+
+	fprintf(stderr, "Testing MGCP.\n");
+	memset(&con, 0, sizeof(con));
+
+	msg = msgb_alloc(4096, "foo");
+	copy_to_msg(msg, ass_cmd, sizeof(ass_cmd));
+	parsed = bsc_nat_parse(msg);
+	if (bsc_mgcp_assign(&con, msg) != 0) {
+		fprintf(stderr, "Failed to handle assignment.\n");
+		abort();
+	}
+
+	if (con.msc_timeslot != 21) {
+		fprintf(stderr, "Timeslot should be 21.\n");
+		abort();
+	}
+
+	if (con.bsc_timeslot != 21) {
+		fprintf(stderr, "Assigned timeslot should have been 21.\n");
+		abort();
+	}
+	talloc_free(parsed);
+
+	bsc_mgcp_clear(&con);
+	if (con.bsc_timeslot != -1 || con.msc_timeslot != -1) {
+		fprintf(stderr, "Clearing should remove the mapping.\n");
+		abort();
+	}
+}
+
 int main(int argc, char **argv)
 {
 	struct debug_target *stderr_target;
@@ -345,9 +380,8 @@
 
 	test_filter();
 	test_contrack();
-
-	debug_set_log_level(stderr_target, 1);
 	test_paging();
+	test_mgcp();
 	return 0;
 }