diff --git a/openbsc/src/ussd.c b/openbsc/src/ussd.c
new file mode 100644
index 0000000..5f9a457
--- /dev/null
+++ b/openbsc/src/ussd.c
@@ -0,0 +1,68 @@
+/* Network-specific handling of mobile-originated USSDs. */
+
+/* (C) 2008-2009 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2008, 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2009 by Mike Haben <michael.haben@btinternet.com>
+ *
+ * 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.
+ *
+ */
+
+/* This module defines the network-specific handling of mobile-originated USSD messages. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include <openbsc/gsm_04_80.h>
+#include <openbsc/gsm_subscriber.h>
+#include <openbsc/debug.h>
+
+/* Declarations of USSD strings to be recognised */
+const char USSD_TEXT_OWN_NUMBER[] = "*#100#";
+
+/* Forward declarations of network-specific handler functions */
+static int send_own_number(struct msgb *msg);
+
+
+/* Entrypoint - handler function common to all mobile-originated USSDs */
+int handle_rcv_ussd(struct msgb *msg)
+{
+	char* ussd_text_rcvd = gsm0480_rcv_ussd(msg);
+
+	if(ussd_text_rcvd[0] == 0xFF)  /* Release-Complete */
+	    return 0;
+
+	if(strstr(USSD_TEXT_OWN_NUMBER, ussd_text_rcvd) != NULL) {
+		DEBUGP(DMM, "USSD: Own number requested\n");
+		return send_own_number(msg);
+	} else {
+		DEBUGP(DMM, "Unhandled USSD %s\n", ussd_text_rcvd);
+		return gsm0480_send_ussd_reject(msg);
+	}
+}
+
+/* A network-specific handler function */
+static int send_own_number(struct msgb *msg)
+{
+	char response_string[] = "Your extension is xxxxx\r"; /* Need trailing CR as EOT character */
+
+	char* own_number = msg->lchan->subscr->extension;
+	memcpy(response_string + 18, own_number, 5);
+	return gsm0480_send_ussd_response(msg, response_string);
+}