diff --git a/src/Makefile b/src/Makefile
index 19887e5..38263b9 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -9,7 +9,7 @@ all: conv_enc_test crc_test tetra-rx float_to_bits tunctl
 libosmo-tetra-phy.a: phy/tetra_burst_sync.o phy/tetra_burst.o
 	$(AR) r $@ $^
 
-libosmo-tetra-mac.a: lower_mac/tetra_conv_enc.o tetra_tdma.o lower_mac/tetra_scramb.o lower_mac/tetra_rm3014.o lower_mac/tetra_interleave.o lower_mac/crc_simple.o tetra_common.o lower_mac/viterbi.o lower_mac/viterbi_cch.o lower_mac/viterbi_tch.o lower_mac/tetra_lower_mac.o tetra_upper_mac.o tetra_mac_pdu.o tetra_llc_pdu.o tetra_llc.o tetra_mle_pdu.o tetra_mm_pdu.o tetra_cmce_pdu.o tetra_sndcp_pdu.o tetra_gsmtap.o tuntap.o
+libosmo-tetra-mac.a: lower_mac/tetra_conv_enc.o lower_mac/tch_reordering.o tetra_tdma.o lower_mac/tetra_scramb.o lower_mac/tetra_rm3014.o lower_mac/tetra_interleave.o lower_mac/crc_simple.o tetra_common.o lower_mac/viterbi.o lower_mac/viterbi_cch.o lower_mac/viterbi_tch.o lower_mac/tetra_lower_mac.o tetra_upper_mac.o tetra_mac_pdu.o tetra_llc_pdu.o tetra_llc.o tetra_mle_pdu.o tetra_mm_pdu.o tetra_cmce_pdu.o tetra_sndcp_pdu.o tetra_gsmtap.o tuntap.o
 	$(AR) r $@ $^
 
 float_to_bits: float_to_bits.o
diff --git a/src/lower_mac/tch_reordering.c b/src/lower_mac/tch_reordering.c
new file mode 100644
index 0000000..00fa4d5
--- /dev/null
+++ b/src/lower_mac/tch_reordering.c
@@ -0,0 +1,140 @@
+/* Bit re-ordering for TETRA ACELP speech codec */
+
+/* (C) 2011 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdint.h>
+#include <string.h>
+
+
+/* EN 300 395-2 V1.3.1 Table 4 */
+
+#define NUM_ACELP_CLASS0_BITS	51
+/* 51 Unprotected Class0 bits */
+static const uint8_t class0_positions[NUM_ACELP_CLASS0_BITS] = {
+	35, 36, 37,
+	38, 39, 40,
+	41, 42, 33,
+	47, 48,
+	56,
+	61, 62, 63,
+	65, 66, 67,
+	68, 69, 70,
+	74, 75,
+	83,
+	88,
+	89, 90, 91,
+	92, 93, 94,
+	95, 96, 97,
+	101, 102,
+	110,
+	115,
+	116, 117, 118,
+	119, 120, 121,
+	122, 123, 124,
+	128, 129,
+	137
+};
+
+#define NUM_ACELP_CLASS1_BITS	56
+static const uint8_t class1_positions[NUM_ACELP_CLASS1_BITS] = {
+	58, 85, 112,
+	54, 81, 108, 135,
+	50, 77,
+	104, 131,
+	45, 72, 99, 126,
+	55, 82, 109, 136,
+	5, 13, 34,
+	8, 16, 17,
+	22, 23, 24,
+	25, 26,
+	6, 14, 7, 15,
+	60, 87 ,114,
+	46,
+	73, 100, 127,
+	44, 71, 98, 125,
+	33, 49,
+	76, 103, 130,
+	59, 86, 113,
+	57, 84, 111
+};
+
+#define NUM_ACELP_CLASS2_BITS	30
+static const uint8_t class2_positions[NUM_ACELP_CLASS2_BITS] = {
+	18, 19, 20, 21,
+	31, 32,
+	53, 80, 107, 134,
+	1, 2, 3, 4,
+	9, 10, 11, 12,
+	27, 28, 29, 30,
+	52, 79, 106, 133,
+	51, 78, 105, 132
+};
+
+#define NUM_ACELP_BITS	(NUM_ACELP_CLASS0_BITS+NUM_ACELP_CLASS1_BITS+NUM_ACELP_CLASS2_BITS)
+
+/* reorder the 432-bit incoming (decoded) type2 bits of a full-rate speech
+ * frame in order to generate two consecutive 216-bit ACELP codec frames */
+void tetra_acelp_type2_to_codec(const uint8_t *in, uint8_t *out)
+{
+	int bit, frame;
+	const uint8_t *in_cur = in;
+
+	for (bit = 0; bit < NUM_ACELP_CLASS0_BITS; bit++) {
+		for (frame = 0; frame < 2; frame++) 
+			out[frame*NUM_ACELP_BITS + class0_positions[bit] - 1] = in_cur[2*bit + frame];
+	}
+	in_cur += 2*NUM_ACELP_CLASS0_BITS;
+
+	for (bit = 0; bit < NUM_ACELP_CLASS1_BITS; bit++) {
+		for (frame = 0; frame < 2; frame++) 
+			out[frame*NUM_ACELP_BITS + class1_positions[bit] - 1] = in_cur[2*bit + frame];
+	}
+	in_cur += 2*NUM_ACELP_CLASS1_BITS;
+
+	for (bit = 0; bit < NUM_ACELP_CLASS2_BITS; bit++) {
+		for (frame = 0; frame < 2; frame++) 
+			out[frame*NUM_ACELP_BITS + class2_positions[bit] - 1] = in_cur[2*bit + frame];
+	}
+
+	/* FIXME: same for STCH use */
+}
+
+void tetra_acelp_codec_to_acelp(const uint8_t *in, uint8_t *out)
+{
+	int bit, frame;
+	uint8_t *out_cur = out;
+
+	for (bit = 0; bit < NUM_ACELP_CLASS0_BITS; bit++) {
+		for (frame = 0; frame < 2; frame++) 
+			out_cur[2*bit + frame] = in[frame*NUM_ACELP_BITS + class0_positions[bit] - 1];
+	}
+	out_cur += 2*NUM_ACELP_CLASS0_BITS;
+
+	for (bit = 0; bit < NUM_ACELP_CLASS1_BITS; bit++) {
+		for (frame = 0; frame < 2; frame++) 
+			out_cur[2*bit + frame] = in[frame*NUM_ACELP_BITS + class1_positions[bit] - 1];
+	}
+	out_cur += 2*NUM_ACELP_CLASS1_BITS;
+
+	for (bit = 0; bit < NUM_ACELP_CLASS2_BITS; bit++) {
+		for (frame = 0; frame < 2; frame++) 
+			out_cur[2*bit + frame] = in[frame*NUM_ACELP_BITS + class2_positions[bit] - 1];
+	}
+}