diff --git a/include/osmocom/sgsn/gprs_sgsn.h b/include/osmocom/sgsn/gprs_sgsn.h
index 9753ea2..336155c 100644
--- a/include/osmocom/sgsn/gprs_sgsn.h
+++ b/include/osmocom/sgsn/gprs_sgsn.h
@@ -156,6 +156,10 @@
 		struct gprs_llc_llme	*llme;
 		uint32_t		tlli;
 		uint32_t		tlli_new;
+
+		/* timer for mm state. state=READY: T3314 (aka TS 23.060 "READY timer") */
+		struct osmo_timer_list  state_timer;
+		unsigned int		state_T;	/* Txxxx number but only used for pmm_states */
 	} gb;
 	struct {
 		int			new_key;
diff --git a/src/gprs/gprs_gmm.c b/src/gprs/gprs_gmm.c
index db8defc..f7aff73 100644
--- a/src/gprs/gprs_gmm.c
+++ b/src/gprs/gprs_gmm.c
@@ -137,6 +137,57 @@
 	}
 }
 
+static void mmctx_set_mm_state(struct sgsn_mm_ctx *ctx, enum gprs_pmm_state state);
+static void mmctx_state_timer_cb(void *_mm)
+{
+	struct sgsn_mm_ctx *mm = _mm;
+
+	switch (mm->gb.state_T) {
+	case 3314:
+		switch (mm->pmm_state) {
+		case MM_READY:
+			LOGMMCTXP(LOGL_INFO, mm, "T3314 expired\n");
+			mmctx_set_mm_state(mm, MM_STANDBY);
+			break;
+		default:
+			LOGMMCTXP(LOGL_ERROR, mm, "T3314 expired in state %s != MM_READY\n",
+				  get_value_string(gprs_pmm_state_names, mm->pmm_state));
+			break;
+		}
+		break;
+	default:
+		LOGMMCTXP(LOGL_ERROR, mm, "state timer expired in unknown mode %u\n",
+			mm->gb.state_T);
+		break;
+	}
+}
+
+static void mmctx_state_timer_start(struct sgsn_mm_ctx *mm, unsigned int T)
+{
+	unsigned long seconds;
+
+	if (mm->gb.state_T && mm->gb.state_T != T)
+		LOGMMCTXP(LOGL_ERROR, mm, "Attempting to start timer %u but %u is active!\n",
+			  T, mm->gb.state_T);
+
+	mm->gb.state_T = T;
+	mm->gb.state_timer.data = mm;
+	mm->gb.state_timer.cb = &mmctx_state_timer_cb;
+
+	seconds = osmo_tdef_get(sgsn->cfg.T_defs, T, OSMO_TDEF_S, -1);
+	osmo_timer_schedule(&mm->gb.state_timer, seconds, 0);
+}
+
+static void mmctx_state_timer_stop(struct sgsn_mm_ctx *mm, unsigned int T)
+{
+	if (mm->gb.state_T == T)
+		osmo_timer_del(&mm->gb.state_timer);
+	else
+		LOGMMCTXP(LOGL_ERROR, mm, "Attempting to stop timer %u but %u is active!\n",
+			  T, mm->gb.state_T);
+	mm->gb.state_T = 0;
+}
+
 static void mmctx_set_pmm_state(struct sgsn_mm_ctx *ctx, enum gprs_pmm_state state)
 {
 	OSMO_ASSERT(ctx->ran_type == MM_CTX_T_UTRAN_Iu);
@@ -173,6 +224,24 @@
 		  get_value_string(gprs_pmm_state_names, ctx->pmm_state),
 		  get_value_string(gprs_pmm_state_names, state));
 
+	switch (state) {
+	case MM_READY:
+		/* on expiration, T3314 moves mm state back to MM_STANDBY */
+		mmctx_state_timer_start(ctx, 3314);
+		break;
+	case MM_IDLE:
+		if (ctx->pmm_state == MM_READY)
+			mmctx_state_timer_stop(ctx, 3314);
+		break;
+	case MM_STANDBY:
+		if (ctx->pmm_state == MM_READY)
+			mmctx_state_timer_stop(ctx, 3314);
+		break;
+	default:
+		/* when changing to state != MM_READY */
+		break;
+	}
+
 	ctx->pmm_state = state;
 }
 
@@ -2968,6 +3037,21 @@
 	return rc;
 }
 
+/* Update the MM context state */
+static void gsm0408_gprs_notify_pdu_gb(struct sgsn_mm_ctx *mmctx)
+{
+	switch (mmctx->pmm_state) {
+	case MM_STANDBY:
+		mmctx_set_mm_state(mmctx, MM_READY);
+		break;
+	case MM_READY: /* RE-arm the timer upon receival of Gb PDUs */
+		mmctx_state_timer_start(mmctx, 3314);
+		break;
+	default:
+		break;
+	}
+}
+
 /* Main entry point for incoming 04.08 GPRS messages from Gb */
 int gsm0408_gprs_rcvmsg_gb(struct msgb *msg, struct gprs_llc_llme *llme,
 			   bool drop_cipherable)
@@ -2988,6 +3072,9 @@
 
 	/* MMCTX can be NULL */
 
+	if (mmctx)
+		gsm0408_gprs_notify_pdu_gb(mmctx);
+
 	switch (pdisc) {
 	case GSM48_PDISC_MM_GPRS:
 		rc = gsm0408_rcv_gmm(mmctx, msg, llme, drop_cipherable);
diff --git a/src/gprs/gprs_sgsn.c b/src/gprs/gprs_sgsn.c
index eb04846..9f02d54 100644
--- a/src/gprs/gprs_sgsn.c
+++ b/src/gprs/gprs_sgsn.c
@@ -341,6 +341,11 @@
 		osmo_timer_del(&mm->timer);
 	}
 
+	if (osmo_timer_pending(&mm->gb.state_timer)) {
+		LOGMMCTXP(LOGL_INFO, mm, "Cancelling MM state timer %u\n", mm->gb.state_T);
+		osmo_timer_del(&mm->gb.state_timer);
+	}
+
 	memset(&sig_data, 0, sizeof(sig_data));
 	sig_data.mm = mm;
 	osmo_signal_dispatch(SS_SGSN, S_SGSN_MM_FREE, &sig_data);
diff --git a/src/gprs/sgsn_vty.c b/src/gprs/sgsn_vty.c
index ae26cbe..6698691 100644
--- a/src/gprs/sgsn_vty.c
+++ b/src/gprs/sgsn_vty.c
@@ -94,7 +94,7 @@
 static struct osmo_tdef sgsn_T_defs[] = {
 	{ .T=3312, .default_val=GSM0408_T3312_SECS, .desc="Periodic RA Update timer (s)" },
 	{ .T=3313, .default_val=GSM0408_T3313_SECS, .desc="Waiting for paging response timer (s)" },
-	{ .T=3314, .default_val=GSM0408_T3314_SECS, .desc="Force to STANDBY on expiry timer (s)" },
+	{ .T=3314, .default_val=GSM0408_T3314_SECS, .desc="READY timer. Force to STANDBY on expiry timer (s)" },
 	{ .T=3316, .default_val=GSM0408_T3316_SECS, .desc="AA-Ready timer (s)" },
 	{ .T=3322, .default_val=GSM0408_T3322_SECS, .desc="Detach request -> accept timer (s)" },
 	{ .T=3350, .default_val=GSM0408_T3350_SECS, .desc="Waiting for ATT/RAU/TMSI_COMPL timer (s)" },
diff --git a/tests/test_nodes.vty b/tests/test_nodes.vty
index 630094f..2ef926a 100644
--- a/tests/test_nodes.vty
+++ b/tests/test_nodes.vty
@@ -2,7 +2,7 @@
 OsmoSGSN# show timer
 T3312 = 600 s	Periodic RA Update timer (s) (default: 600 s)
 T3313 = 30 s	Waiting for paging response timer (s) (default: 30 s)
-T3314 = 44 s	Force to STANDBY on expiry timer (s) (default: 44 s)
+T3314 = 44 s	READY timer. Force to STANDBY on expiry timer (s) (default: 44 s)
 T3316 = 44 s	AA-Ready timer (s) (default: 44 s)
 T3322 = 6 s	Detach request -> accept timer (s) (default: 6 s)
 T3350 = 6 s	Waiting for ATT/RAU/TMSI_COMPL timer (s) (default: 6 s)