diff --git a/src/host/layer23/include/osmocom/bb/mobile/gsm48_rr.h b/src/host/layer23/include/osmocom/bb/mobile/gsm48_rr.h
index 38ac3611f..201216955 100644
--- a/src/host/layer23/include/osmocom/bb/mobile/gsm48_rr.h
+++ b/src/host/layer23/include/osmocom/bb/mobile/gsm48_rr.h
@@ -5,6 +5,11 @@
 
 #define GSM_TA_CM			55385
 
+#define	T200_DCCH			1	/* SDCCH/FACCH */
+#define	T200_DCCH_SHARED		2	/* SDCCH shares SAPI 0 and 3 */
+#define	T200_ACCH			2	/* SACCH SAPI 3 */
+
+
 /* GSM 04.07 9.1.2 */
 #define	GSM48_RR_EST_REQ		0x10
 #define	GSM48_RR_EST_IND		0x12
diff --git a/src/host/layer23/src/mobile/app_mobile.c b/src/host/layer23/src/mobile/app_mobile.c
index d911ab386..dc57c3158 100644
--- a/src/host/layer23/src/mobile/app_mobile.c
+++ b/src/host/layer23/src/mobile/app_mobile.c
@@ -167,6 +167,12 @@ int mobile_init(struct osmocom_ms *ms)
 	gsm_settings_arfcn(ms);
 
 	lapdm_channel_init(&ms->lapdm_channel, LAPDM_MODE_MS);
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI3].dl.t200_sec =
+		T200_DCCH_SHARED;
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI3].dl.t200_usec = 0;
+	ms->lapdm_channel.lapdm_acch.datalink[DL_SAPI3].dl.t200_sec =
+		T200_ACCH;
+	ms->lapdm_channel.lapdm_acch.datalink[DL_SAPI3].dl.t200_usec = 0;
 	lapdm_channel_set_l1(&ms->lapdm_channel, l1ctl_ph_prim_cb, ms);
 
 	gsm_sim_init(ms);
diff --git a/src/host/layer23/src/mobile/gsm48_rr.c b/src/host/layer23/src/mobile/gsm48_rr.c
index bc244699d..36488606c 100644
--- a/src/host/layer23/src/mobile/gsm48_rr.c
+++ b/src/host/layer23/src/mobile/gsm48_rr.c
@@ -3284,6 +3284,11 @@ static int gsm48_rr_dl_est(struct osmocom_ms *ms)
 	gsm48_rr_activate_channel(ms, &rr->cd_now, ma, ma_len);
 #endif
 
+	/* set T200 of SAPI 0 */
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_sec =
+		T200_DCCH;
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_usec = 0;
+
 	/* start establishmnet */
 	return gsm48_send_rsl(ms, RSL_MT_EST_REQ, nmsg, 0);
 }
@@ -3623,6 +3628,11 @@ static int gsm48_rr_tx_ass_cpl(struct osmocom_ms *ms, uint8_t cause)
 	/* RR_CAUSE */
 	ac->rr_cause = cause;
 
+	/* set T200 of SAPI 0 */
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_sec =
+		T200_DCCH;
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_usec = 0;
+
 	return gsm48_send_rsl(ms, RSL_MT_RES_REQ, nmsg, 0);
 }
 
@@ -3990,6 +4000,11 @@ static int gsm48_rr_tx_hando_cpl(struct osmocom_ms *ms, uint8_t cause)
 
 	// FIXME: mobile observed time
 
+	/* set T200 of SAPI 0 */
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_sec =
+		T200_DCCH;
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_usec = 0;
+
 	return gsm48_send_rsl(ms, RSL_MT_RES_REQ, nmsg, 0);
 }
 
@@ -5025,6 +5040,13 @@ static int gsm48_rr_estab_ind_sapi3(struct osmocom_ms *ms, struct msgb *msg)
 
 	LOGP(DSUM, LOGL_INFO, "Radio link SAPI3 is established\n");
 
+	if ((link_id & 0xf8) == 0x00) {
+		/* raise T200 of SAPI 0 */
+		ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_sec =
+			T200_DCCH_SHARED;
+		ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_usec= 0;
+	}
+
 	/* send inication to upper layer */
 	nmsg = gsm48_rr_msgb_alloc(GSM48_RR_EST_IND);
 	if (!nmsg)
@@ -5101,6 +5123,11 @@ static int gsm48_rr_rel_ind_sapi3(struct osmocom_ms *ms, struct msgb *msg)
 
 	LOGP(DSUM, LOGL_INFO, "Radio link SAPI3 is released\n");
 
+	/* lower T200 of SAPI 0 */
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_sec =
+		T200_DCCH;
+	ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_usec = 0;
+
 	/* send inication to upper layer */
 	nmsg = gsm48_rr_msgb_alloc(GSM48_RR_REL_IND);
 	if (!nmsg)
@@ -5140,6 +5167,10 @@ static int gsm48_rr_est_req_sapi3(struct osmocom_ms *ms, struct msgb *msg)
 		LOGP(DRR, LOGL_INFO, "Requesting DCCH link, because no TCH "
 			"(sapi %d)\n", sapi);
 		rr->sapi3_link_id = 0x00 | sapi; /* SAPI 3, DCCH */
+		/* raise T200 of SAPI 0 */
+		ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_sec =
+			T200_DCCH_SHARED;
+		ms->lapdm_channel.lapdm_dcch.datalink[DL_SAPI0].dl.t200_usec= 0;
 	} else {
 		LOGP(DRR, LOGL_INFO, "Requesting ACCH link, because TCH "
 			"(sapi %d)\n", sapi);