diff --git a/src/gprs_ms.c b/src/gprs_ms.c
index 5733a7c..c072b0a 100644
--- a/src/gprs_ms.c
+++ b/src/gprs_ms.c
@@ -1085,7 +1085,10 @@
 	LOGPTBFDL(dl_tbf, LOGL_DEBUG, "[DOWNLINK] START\n");
 
 	/* Trigger the assignment now. */
-	tbf_dl_trigger_ass(dl_tbf, ul_tbf_as_tbf(ul_tbf));
+	if (ul_tbf)
+		dl_tbf_trigger_ass_on_pacch(dl_tbf, ul_tbf_as_tbf(ul_tbf));
+	else
+		dl_tbf_trigger_ass_on_pch(dl_tbf);
 	return 0;
 }
 
diff --git a/src/tbf.cpp b/src/tbf.cpp
index d115b82..4bf4ce8 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -703,7 +703,7 @@
 	}
 
 	LOGPTBF(this, LOGL_DEBUG, "Trigger downlink assignment on PACCH\n");
-	new_tbf->trigger_ass(this);
+	dl_tbf_trigger_ass_on_pacch(new_tbf, this);
 
 	return 0;
 }
@@ -960,3 +960,8 @@
 {
 	return tbf->trx;
 }
+
+void tbf_stop_timers(struct gprs_rlcmac_tbf *tbf, const char *reason)
+{
+	tbf->stop_timers(reason);
+}
\ No newline at end of file
diff --git a/src/tbf.h b/src/tbf.h
index d69ae5a..09de188 100644
--- a/src/tbf.h
+++ b/src/tbf.h
@@ -150,6 +150,7 @@
 int tbf_update(struct gprs_rlcmac_tbf *tbf);
 int tbf_establish_dl_tbf_on_pacch(struct gprs_rlcmac_tbf *tbf);
 struct gprs_rlcmac_trx *tbf_get_trx(struct gprs_rlcmac_tbf *tbf);
+void tbf_stop_timers(struct gprs_rlcmac_tbf *tbf, const char *reason);
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index 0936e1c..856dae6 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -418,29 +418,41 @@
 	return create_dl_acked_block(fn, ts, bsn, bsn2);
 }
 
-/* depending on the current TBF, we assign on PACCH or AGCH */
-void gprs_rlcmac_dl_tbf::trigger_ass(struct gprs_rlcmac_tbf *old_tbf)
+/* old_tbf (UL TBF or DL TBF) will send a Pkt Dl Ass on PACCH to assign tbf.
+ * Note: It is possible that "tbf == old_tbf" if the TBF is being updated. This can
+ * happen when we first assign over PCH (only single slot is possible) and we want
+ * to upgrade the DL-TBF to be multislot. See code calling tbf_update() for more
+ * information.
+ */
+void dl_tbf_trigger_ass_on_pacch(struct gprs_rlcmac_dl_tbf *tbf, struct gprs_rlcmac_tbf *old_tbf)
+{
+	OSMO_ASSERT(tbf);
+	OSMO_ASSERT(old_tbf);
+	/* stop pending timer */
+	tbf_stop_timers(tbf, "DL assignment (PACCH)");
+
+	LOGPTBFDL(tbf, LOGL_DEBUG, "Send downlink assignment on PACCH, because %s exists\n", old_tbf->name());
+	osmo_fsm_inst_dispatch(old_tbf->dl_ass_fsm.fi, TBF_DL_ASS_EV_SCHED_ASS, NULL);
+
+	/* change state */
+	osmo_fsm_inst_dispatch(tbf->state_fsm.fi, TBF_EV_ASSIGN_ADD_PACCH, NULL);
+
+}
+
+void dl_tbf_trigger_ass_on_pch(struct gprs_rlcmac_dl_tbf *tbf)
 {
 	/* stop pending timer */
-	stop_timers("assignment (DL-TBF)");
+	struct GprsMs *ms = tbf_ms(tbf);
 
-	/* check for downlink tbf:  */
-	if (old_tbf) {
-		LOGPTBFDL(this, LOGL_DEBUG, "Send downlink assignment on PACCH, because %s exists\n", old_tbf->name());
-		osmo_fsm_inst_dispatch(old_tbf->dl_ass_fsm.fi, TBF_DL_ASS_EV_SCHED_ASS, NULL);
+	tbf_stop_timers(tbf, "DL assignment (PCH)");
 
-		/* change state */
-		osmo_fsm_inst_dispatch(this->state_fsm.fi, TBF_EV_ASSIGN_ADD_PACCH, NULL);
-	} else {
-		LOGPTBFDL(this, LOGL_DEBUG, "Send downlink assignment on PCH, no TBF exist (IMSI=%s)\n",
-			  imsi());
+	LOGPTBFDL(tbf, LOGL_DEBUG, "Send downlink assignment on PCH, no TBF exist (IMSI=%s)\n", ms_imsi(ms));
 
-		/* change state */
-		osmo_fsm_inst_dispatch(this->state_fsm.fi, TBF_EV_ASSIGN_ADD_CCCH, NULL);
+	/* change state */
+	osmo_fsm_inst_dispatch(tbf->state_fsm.fi, TBF_EV_ASSIGN_ADD_CCCH, NULL);
 
-		/* send immediate assignment */
-		bts_snd_dl_ass(bts, this);
-	}
+	/* send immediate assignment */
+	bts_snd_dl_ass(ms->bts, tbf);
 }
 
 void gprs_rlcmac_dl_tbf::schedule_next_frame()
@@ -1272,8 +1284,3 @@
 	else
 		return NULL;
 }
-
-void tbf_dl_trigger_ass(struct gprs_rlcmac_dl_tbf *tbf, struct gprs_rlcmac_tbf *old_tbf)
-{
-	return tbf->trigger_ass(old_tbf);
-}
diff --git a/src/tbf_dl.h b/src/tbf_dl.h
index e0daf57..ba5d582 100644
--- a/src/tbf_dl.h
+++ b/src/tbf_dl.h
@@ -41,7 +41,6 @@
 
 	int rcvd_dl_ack(bool final_ack, unsigned first_bsn, struct bitvec *rbb);
 	struct msgb *create_dl_acked_block(uint32_t fn, uint8_t ts, enum mcs_kind req_mcs_kind = EGPRS);
-	void trigger_ass(struct gprs_rlcmac_tbf *old_tbf);
 
 	void request_dl_ack();
 	bool need_poll_for_dl_ack_nack() const;
@@ -138,7 +137,8 @@
 		  const uint8_t egprs_ms_class, const uint16_t delay_csec,
 		  const uint8_t *data, const uint16_t len);
 
-void tbf_dl_trigger_ass(struct gprs_rlcmac_dl_tbf *tbf, struct gprs_rlcmac_tbf *old_tbf);
+void dl_tbf_trigger_ass_on_pacch(struct gprs_rlcmac_dl_tbf *tbf, struct gprs_rlcmac_tbf *old_tbf);
+void dl_tbf_trigger_ass_on_pch(struct gprs_rlcmac_dl_tbf *tbf);
 void tbf_dl_request_dl_ack(struct gprs_rlcmac_dl_tbf *tbf);
 
 static inline struct gprs_rlcmac_tbf *dl_tbf_as_tbf(struct gprs_rlcmac_dl_tbf *dl_tbf)
diff --git a/src/tbf_fsm.c b/src/tbf_fsm.c
index 25253fd..eeccd6b 100644
--- a/src/tbf_fsm.c
+++ b/src/tbf_fsm.c
@@ -387,8 +387,7 @@
 		ctx->state_flags &= GPRS_RLCMAC_FLAG_TO_MASK;
 
 		tbf_update(ctx->tbf);
-
-		tbf_dl_trigger_ass(dl_tbf, ctx->tbf);
+		dl_tbf_trigger_ass_on_pacch(dl_tbf, ctx->tbf);
 	} else
 		LOGPTBF(ctx->tbf, LOGL_NOTICE, "Continue flow after IMM.ASS confirm\n");
 }