diff --git a/openbsc/include/openbsc/mncc.h b/openbsc/include/openbsc/mncc.h
index 4a99bb1..ffc247b 100644
--- a/openbsc/include/openbsc/mncc.h
+++ b/openbsc/include/openbsc/mncc.h
@@ -95,6 +95,7 @@
 
 #define GSM_TCHF_FRAME		0x0300
 #define GSM_TCHF_FRAME_EFR	0x0301
+#define GSM_TCHF_BAD_FRAME	0x03ff
 
 #define MNCC_SOCKET_HELLO	0x0400
 
diff --git a/openbsc/include/openbsc/trau_mux.h b/openbsc/include/openbsc/trau_mux.h
index 2c01b06..3de50f7 100644
--- a/openbsc/include/openbsc/trau_mux.h
+++ b/openbsc/include/openbsc/trau_mux.h
@@ -53,3 +53,13 @@
 
 /* callback invoked if we receive TRAU frames */
 int subch_cb(struct subch_demux *dmx, int ch, uint8_t *data, int len, void *_priv);
+
+/* TRAU frame transcoding */
+struct msgb *trau_decode_fr(uint32_t callref,
+	const struct decoded_trau_frame *tf);
+struct msgb *trau_decode_efr(uint32_t callref,
+	const struct decoded_trau_frame *tf);
+void trau_encode_fr(struct decoded_trau_frame *tf,
+	const unsigned char *data);
+void trau_encode_efr(struct decoded_trau_frame *tf,
+	const unsigned char *data);