diff --git a/src/tetra_mac_pdu.c b/src/tetra_mac_pdu.c
index 70b5ec9..b395b7c 100644
--- a/src/tetra_mac_pdu.c
+++ b/src/tetra_mac_pdu.c
@@ -39,28 +39,45 @@ static void decode_d_mle_sysinfo(struct tetra_mle_si_decoded *msid, const uint8_
 	msid->bs_service_details = bits_to_uint(cur, 12); cur += 12;
 }
 
+/* see 21.4.4.1 */
 void macpdu_decode_sysinfo(struct tetra_si_decoded *sid, const uint8_t *si_bits)
 {
-	const uint8_t *cur = si_bits + 4;
+	const uint8_t *cur     = si_bits;
+	cur += 2; // skip Broadcast PDU header
+	cur += 2; // skip Sysinfo PDU header
 
-	sid->main_carrier = bits_to_uint(cur, 12); cur += 12;
-	sid->freq_band = bits_to_uint(cur, 4); cur += 4;
-	sid->freq_offset = bits_to_uint(cur, 2); cur += 2;
-	sid->duplex_spacing = bits_to_uint(cur, 3); cur += 3;
+	sid->main_carrier      = bits_to_uint(cur, 12); cur += 12;
+	sid->freq_band         = bits_to_uint(cur,  4); cur +=  4;
+	sid->freq_offset       = bits_to_uint(cur,  2); cur +=  2;
+	sid->duplex_spacing    = bits_to_uint(cur,  3); cur +=  3;
 	sid->reverse_operation = *cur++;
-	sid->num_of_csch = bits_to_uint(cur, 2); cur +=2;
-	sid->ms_txpwr_max_cell = bits_to_uint(cur, 3); cur += 3;
-	sid->rxlev_access_min = bits_to_uint(cur, 4); cur += 4;
-	sid->access_parameter = bits_to_uint(cur, 4); cur += 4;
-	sid->radio_dl_timeout = bits_to_uint(cur, 4); cur += 4;
-	sid->cck_valid_no_hf = *cur++;
+	sid->num_of_csch       = bits_to_uint(cur,  2); cur +=  2;
+	sid->ms_txpwr_max_cell = bits_to_uint(cur,  3); cur +=  3;
+	sid->rxlev_access_min  = bits_to_uint(cur,  4); cur +=  4;
+	sid->access_parameter  = bits_to_uint(cur,  4); cur +=  4;
+	sid->radio_dl_timeout  = bits_to_uint(cur,  4); cur +=  4;
+	sid->cck_valid_no_hf   = *cur++;
 	if (sid->cck_valid_no_hf)
 		sid->cck_id = bits_to_uint(cur, 16);
 	else
 		sid->hyperframe_number = bits_to_uint(cur, 16);
-	cur += 16;
-	/* FIXME: more */
-	decode_d_mle_sysinfo(&sid->mle_si, si_bits + 124-42);
+	
+	sid->option_field      = bits_to_uint(cur,  2); cur +=  2;
+	switch(sid->option_field)
+	{
+	  case TETRA_MAC_OPT_FIELD_EVEN_MULTIFRAME:     // Even multiframe definition for TS mode
+	  case TETRA_MAC_OPT_FIELD_ODD_MULTIFRAME:      // Odd multiframe definition for TS mode
+	    sid->frame_bitmap = bits_to_uint(cur, 20); cur += 20;
+	    break;
+	  case TETRA_MAC_OPT_FIELD_ACCESS_CODE:         // Default definition for access code A
+	    sid->access_code = bits_to_uint(cur, 20); cur += 20;
+	    break;
+	  case TETRA_MAC_OPT_FIELD_EXT_SERVICES:        // Extended services broadcast
+	    sid->ext_service = bits_to_uint(cur, 20); cur += 20;
+	    break;
+	}
+
+	decode_d_mle_sysinfo(&sid->mle_si, si_bits + 124-42);  // could be also cur due to previous fixes
 }
 
 static const uint8_t addr_len_by_type[] = {
diff --git a/src/tetra_mac_pdu.h b/src/tetra_mac_pdu.h
index 74608a6..051e47a 100644
--- a/src/tetra_mac_pdu.h
+++ b/src/tetra_mac_pdu.h
@@ -36,6 +36,13 @@ enum tetra_bs_serv_details {
 	BS_SERVDET_ADV_LINK	= (1 << 0),
 };
 
+enum tetra_mac_optional_field_flags {
+	TETRA_MAC_OPT_FIELD_EVEN_MULTIFRAME = 0,
+	TETRA_MAC_OPT_FIELD_ODD_MULTIFRAME  = 1,
+	TETRA_MAC_OPT_FIELD_ACCESS_CODE     = 2,
+	TETRA_MAC_OPT_FIELD_EXT_SERVICES    = 3
+};
+
 const char *tetra_get_bs_serv_det_name(uint32_t pdu_type);
 
 struct tetra_mle_si_decoded {
@@ -60,6 +67,12 @@ struct tetra_si_decoded {
 		uint16_t cck_id;
 		uint16_t hyperframe_number;
 	};
+	uint8_t option_field;
+	union {
+		uint32_t frame_bitmap;
+		uint32_t access_code;
+		uint32_t ext_service;
+	};
 	struct tetra_mle_si_decoded mle_si;
 };
 
diff --git a/src/tetra_prim.h b/src/tetra_prim.h
index 9bbb830..8913187 100644
--- a/src/tetra_prim.h
+++ b/src/tetra_prim.h
@@ -9,7 +9,7 @@
 
 enum tetra_saps {
 	TETRA_SAP_TP,	/* between PHY and lower MAC */
-	TETRA_SAP_TMV,	/* beetween lower and upper MAC */
+	TETRA_SAP_TMV,	/* between lower and upper MAC */
 	TETRA_SAP_TMA,
 	TETRA_SAP_TMB,
 	TETRA_SAP_TMD,
diff --git a/src/tetra_tdma.c b/src/tetra_tdma.c
index 8fffa39..e138f49 100644
--- a/src/tetra_tdma.c
+++ b/src/tetra_tdma.c
@@ -95,6 +95,5 @@ char *tetra_tdma_time_dump(const struct tetra_tdma_time *tm)
 
 uint32_t tetra_tdma_time2fn(struct tetra_tdma_time *tm)
 {
-	/* FIXME: add hyperframe number !! */
-	return (tm->mn *18) + tm->fn;
+	return (((tm->hn * 60) + tm->mn) * 18) + tm->fn;
 }
diff --git a/src/tetra_tdma.h b/src/tetra_tdma.h
index 86c17af..01519ee 100644
--- a/src/tetra_tdma.h
+++ b/src/tetra_tdma.h
@@ -4,6 +4,7 @@
 #include <stdint.h>
 
 struct tetra_tdma_time {
+	uint16_t hn;    /* hyperframe number (1 ... 65535) */
 	uint32_t sn;	/* symbol number (1 ... 255) */
 	uint32_t tn;	/* timeslot number (1 .. 4) */
 	uint32_t fn;	/* frame number (1 .. 18) */
diff --git a/src/tetra_upper_mac.c b/src/tetra_upper_mac.c
index e5b9f30..fdc8c73 100644
--- a/src/tetra_upper_mac.c
+++ b/src/tetra_upper_mac.c
@@ -49,6 +49,7 @@ static void rx_bcast(struct tetra_tmvsap_prim *tmvp, struct tetra_mac_state *tms
 
 	memset(&sid, 0, sizeof(sid));
 	macpdu_decode_sysinfo(&sid, msg->l1h);
+	tmvp->u.unitdata.tdma_time.hn = sid.hyperframe_number;
 
 	dl_freq = tetra_dl_carrier_hz(sid.freq_band,
 				      sid.main_carrier,