diff --git a/openbsc/include/openbsc/gsm_04_80.h b/openbsc/include/openbsc/gsm_04_80.h
new file mode 100644
index 0000000..11962d8
--- /dev/null
+++ b/openbsc/include/openbsc/gsm_04_80.h
@@ -0,0 +1,132 @@
+#ifndef _GSM_04_80_H
+#define _GSM_04_80_H
+
+/* GSM TS 04.80  definitions (Supplementary Services Specification, Formats and Coding) */
+
+/* Section 3.4 */
+#define GSM0480_MTYPE_RELEASE_COMPLETE	0x2A
+#define GSM0480_MTYPE_FACILITY			0x3A
+#define GSM0480_MTYPE_REGISTER			0x3B
+
+/* Section 3.5 */
+#define GSM0480_IE_FACILITY			0x1C
+#define GSM0480_IE_SS_VERSION			0x7F
+
+/* Section 3.6.2 */
+#define GSM0480_CTYPE_INVOKE			0xA1
+#define GSM0480_CTYPE_RETURN_RESULT		0xA2
+#define GSM0480_CTYPE_RETURN_ERROR		0xA3
+#define GSM0480_CTYPE_REJECT			0xA4
+
+/* Section 3.6.3 */
+#define GSM0480_COMPIDTAG_INVOKE_ID		0x02
+#define GSM0480_COMPIDTAG_LINKED_ID		0x80
+
+/* Section 3.6.4 */
+#define GSM0480_OPERATION_CODE			0x02
+
+/* Section 3.6.5 */
+#define GSM_0480_SEQUENCE_TAG			0x30
+#define GSM_0480_SET_TAG			0x31
+
+/* Section 3.6.6 */
+#define GSM_0480_ERROR_CODE_TAG			0x02
+
+/* Section 3.6.7 */
+/* Table 3.13 */
+#define GSM_0480_PROBLEM_CODE_TAG_GENERAL	0x80
+#define GSM_0480_PROBLEM_CODE_TAG_INVOKE	0x81
+#define GSM_0480_PROBLEM_CODE_TAG_RETURN_RESULT	0x82
+#define GSM_0480_PROBLEM_CODE_TAG_RETURN_ERROR	0x83
+
+/* Table 3.14 */
+#define GSM_0480_GEN_PROB_CODE_UNRECOGNISED	0x00
+#define GSM_0480_GEN_PROB_CODE_MISTYPED		0x01
+#define GSM_0480_GEN_PROB_CODE_BAD_STRUCTURE	0x02
+
+/* Table 3.15 */
+#define GSM_0480_INVOKE_PROB_CODE_DUPLICATE_INVOKE_ID		0x00
+#define GSM_0480_INVOKE_PROB_CODE_UNRECOGNISED_OPERATION	0x01
+#define GSM_0480_INVOKE_PROB_CODE_MISTYPED_PARAMETER		0x02
+#define GSM_0480_INVOKE_PROB_CODE_RESOURCE_LIMITATION		0x03
+#define GSM_0480_INVOKE_PROB_CODE_INITIATING_RELEASE		0x04
+#define GSM_0480_INVOKE_PROB_CODE_UNRECOGNISED_LINKED_ID	0x05
+#define GSM_0480_INVOKE_PROB_CODE_UNEXPECTED_LINKED_RESPONSE	0x06
+#define GSM_0480_INVOKE_PROB_CODE_UNEXPECTED_LINKED_OPERATION	0x07
+
+/* Table 3.16 */
+#define GSM_0480_RESULT_PROB_CODE_UNRECOGNISED_INVOKE_ID	0x00
+#define GSM_0480_RESULT_PROB_CODE_RETURN_RESULT_UNEXPECTED	0x01
+#define GSM_0480_RESULT_PROB_CODE_MISTYPED_PARAMETER		0x02
+
+/* Table 3.17 */
+#define GSM_0480_ERROR_PROB_CODE_UNRECOGNISED_INVOKE_ID		0x00
+#define GSM_0480_ERROR_PROB_CODE_RETURN_ERROR_UNEXPECTED	0x01
+#define GSM_0480_ERROR_PROB_CODE_UNRECOGNISED_ERROR		0x02
+#define GSM_0480_ERROR_PROB_CODE_UNEXPECTED_ERROR		0x03
+#define GSM_0480_ERROR_PROB_CODE_MISTYPED_PARAMETER		0x04
+
+/* Section 4.5 */
+#define GSM0480_OP_CODE_REGISTER_SS		0x0A
+#define GSM0480_OP_CODE_ERASE_SS		0x0B
+#define GSM0480_OP_CODE_ACTIVATE_SS		0x0C
+#define GSM0480_OP_CODE_DEACTIVATE_SS		0x0D
+#define GSM0480_OP_CODE_INTERROGATE_SS		0x0E
+#define GSM0480_OP_CODE_NOTIFY_SS		0x10
+#define GSM0480_OP_CODE_REGISTER_PASSWORD	0x11
+#define GSM0480_OP_CODE_GET_PASSWORD		0x12
+#define GSM0480_OP_CODE_PROCESS_USS_DATA	0x13
+#define GSM0480_OP_CODE_FORWARD_CHECK_SS_IND	0x26
+#define GSM0480_OP_CODE_PROCESS_USS_REQ		0x3B
+#define GSM0480_OP_CODE_USS_REQUEST		0x3C
+#define GSM0480_OP_CODE_USS_NOTIFY		0x3D
+#define GSM0480_OP_CODE_FORWARD_CUG_INFO	0x78
+#define GSM0480_OP_CODE_SPLIT_MPTY		0x79
+#define GSM0480_OP_CODE_RETRIEVE_MPTY		0x7A
+#define GSM0480_OP_CODE_HOLD_MPTY		0x7B
+#define GSM0480_OP_CODE_BUILD_MPTY		0x7C
+#define GSM0480_OP_CODE_FORWARD_CHARGE_ADVICE	0x7D
+
+#define GSM0480_ERR_CODE_UNKNOWN_SUBSCRIBER			0x01
+#define GSM0480_ERR_CODE_ILLEGAL_SUBSCRIBER			0x09
+#define GSM0480_ERR_CODE_BEARER_SERVICE_NOT_PROVISIONED		0x0A
+#define GSM0480_ERR_CODE_TELESERVICE_NOT_PROVISIONED		0x0B
+#define GSM0480_ERR_CODE_ILLEGAL_EQUIPMENT			0x0C
+#define GSM0480_ERR_CODE_CALL_BARRED				0x0D
+#define GSM0480_ERR_CODE_ILLEGAL_SS_OPERATION			0x10
+#define GSM0480_ERR_CODE_SS_ERROR_STATUS			0x11
+#define GSM0480_ERR_CODE_SS_NOT_AVAILABLE			0x12
+#define GSM0480_ERR_CODE_SS_SUBSCRIPTION_VIOLATION		0x13
+#define GSM0480_ERR_CODE_SS_INCOMPATIBILITY			0x14
+#define GSM0480_ERR_CODE_FACILITY_NOT_SUPPORTED			0x15
+#define GSM0480_ERR_CODE_ABSENT_SUBSCRIBER			0x1B
+#define GSM0480_ERR_CODE_SYSTEM_FAILURE				0x22
+#define GSM0480_ERR_CODE_DATA_MISSING				0x23
+#define GSM0480_ERR_CODE_UNEXPECTED_DATA_VALUE			0x24
+#define GSM0480_ERR_CODE_PW_REGISTRATION_FAILURE		0x25
+#define GSM0480_ERR_CODE_NEGATIVE_PW_CHECK			0x26
+#define GSM0480_ERR_CODE_NUM_PW_ATTEMPTS_VIOLATION		0x2B
+#define GSM0480_ERR_CODE_UNKNOWN_ALPHABET			0x47
+#define GSM0480_ERR_CODE_USSD_BUSY				0x48
+#define GSM0480_ERR_CODE_MAX_MPTY_PARTICIPANTS			0x7E
+#define GSM0480_ERR_CODE_RESOURCES_NOT_AVAILABLE		0x7F
+
+/* ASN.1 type-tags */
+#define ASN1_BOOLEAN_TAG		0x01
+#define ASN1_INTEGER_TAG		0x02
+#define ASN1_BIT_STRING_TAG		0x03
+#define ASN1_OCTET_STRING_TAG		0x04
+#define ASN1_NULL_TYPE_TAG		0x05
+#define ASN1_OBJECT_ID_TAG		0x06
+#define ASN1_UTF8_STRING_TAG		0x0C
+#define ASN1_PRINTABLE_STRING_TAG	0x13
+#define ASN1_IA5_STRING_TAG		0x16
+#define ASN1_UNICODE_STRING_TAG		0x1E
+
+#include <openbsc/msgb.h>
+
+char* gsm0480_rcv_ussd(struct msgb *msg);
+int gsm0480_send_ussd_response(struct msgb *msg, const char* response_text);
+int gsm0480_send_ussd_reject(struct msgb *msg);
+
+#endif
diff --git a/openbsc/include/openbsc/ussd.h b/openbsc/include/openbsc/ussd.h
new file mode 100644
index 0000000..e7bd6d6
--- /dev/null
+++ b/openbsc/include/openbsc/ussd.h
@@ -0,0 +1,10 @@
+#ifndef _USSD_H
+#define _USSD_H
+
+/* Handler function for mobile-originated USSD messages */
+
+#include <openbsc/msgb.h>
+
+int handle_rcv_ussd(struct msgb *msg);
+
+#endif