diff --git a/include/osmocom/gsm/protocol/ipaccess.h b/include/osmocom/gsm/protocol/ipaccess.h
index 2792572..5d98a21 100644
--- a/include/osmocom/gsm/protocol/ipaccess.h
+++ b/include/osmocom/gsm/protocol/ipaccess.h
@@ -33,6 +33,7 @@
 	IPAC_PROTO_EXT_CTRL	= 0x00,
 	IPAC_PROTO_EXT_MGCP	= 0x01,
 	IPAC_PROTO_EXT_LAC	= 0x02,
+	IPAC_PROTO_EXT_SMSC	= 0x03,
 };
 
 enum ipaccess_msgtype {