diff --git a/include/osmo-bts/scheduler.h b/include/osmo-bts/scheduler.h
index c96b70b46..40b429392 100644
--- a/include/osmo-bts/scheduler.h
+++ b/include/osmo-bts/scheduler.h
@@ -240,6 +240,7 @@ extern const struct trx_sched_multiframe trx_sched_multiframes[];
 #define TRX_BI_F_TRX_NUM	(1 << 4)
 #define TRX_BI_F_BATCH_IND	(1 << 5)
 #define TRX_BI_F_SHADOW_IND	(1 << 6)
+#define TRX_BI_F_ACCESS_BURST	(1 << 7)
 
 /*! UL burst indication with the corresponding meta info */
 struct trx_ul_burst_ind {
diff --git a/src/osmo-bts-trx/sched_lchan_pdtch.c b/src/osmo-bts-trx/sched_lchan_pdtch.c
index 92bb5a81d..8300bdbbe 100644
--- a/src/osmo-bts-trx/sched_lchan_pdtch.c
+++ b/src/osmo-bts-trx/sched_lchan_pdtch.c
@@ -56,6 +56,10 @@ int rx_pdtch_fn(struct l1sched_ts *l1ts, const struct trx_ul_burst_ind *bi)
 
 	LOGL1SB(DL1P, LOGL_DEBUG, l1ts, bi, "Received PDTCH bid=%u\n", bi->bid);
 
+	/* An MS may be polled to send an ACK in form of four Access Bursts */
+	if (bi->flags & TRX_BI_F_ACCESS_BURST)
+		return rx_rach_fn(l1ts, bi);
+
 	/* allocate burst memory, if not already */
 	if (!*bursts_p) {
 		*bursts_p = talloc_zero_size(l1ts, GSM0503_EGPRS_BURSTS_NBITS);
diff --git a/src/osmo-bts-trx/trx_if.c b/src/osmo-bts-trx/trx_if.c
index ba2978866..bb9404c8f 100644
--- a/src/osmo-bts-trx/trx_if.c
+++ b/src/osmo-bts-trx/trx_if.c
@@ -826,13 +826,18 @@ static inline int trx_data_parse_mts(struct phy_instance *phy_inst,
 
 	/* | 7 6 5 4 3 2 1 0 | Bitmask / description
 	 * | . 0 0 X X . . . | GMSK, 4 TSC sets (0..3)
-	 * | . 0 1 0 X . . . | 8-PSK, 2 TSC sets (0..1) */
+	 * | . 0 1 0 X . . . | 8-PSK, 2 TSC sets (0..1)
+	 * | . 0 1 1 0 . . . | GMSK, Access Burst */
 	if ((mts >> 5) == 0x00) {
 		bi->mod = TRX_MOD_T_GMSK;
 		bi->tsc_set = (mts >> 3) & 0x03;
 	} else if ((mts >> 4) == 0x02) {
 		bi->mod = TRX_MOD_T_8PSK;
 		bi->tsc_set = (mts >> 3) & 0x01;
+	} else if ((mts >> 3) == 0x06) {
+		bi->flags |= TRX_BI_F_ACCESS_BURST;
+		bi->mod = TRX_MOD_T_GMSK;
+		bi->tsc_set = 0;
 	} else {
 		LOGPPHI(phy_inst, DTRX, LOGL_ERROR,
 			"Rx TRXD PDU with unknown or not supported "