diff --git a/src/libmsc/gsm_04_11.c b/src/libmsc/gsm_04_11.c
index ae19b2762..5c2692944 100644
--- a/src/libmsc/gsm_04_11.c
+++ b/src/libmsc/gsm_04_11.c
@@ -629,6 +629,10 @@ static int gsm340_rx_tpdu(struct gsm_trans *trans, struct msgb *msg,
 
 	rc = sms_route_mt_sms(trans, gsms);
 
+	/* This SMS got routed through SMPP and we are waiting on the response. */
+	if (gsms->smpp.esme) {
+		return -EINPROGRESS;
+	}
 	/*
 	 * This SMS got routed through SMPP or no receiver exists.
 	 * In any case, we store it in the database for further processing.
@@ -717,8 +721,10 @@ static int gsm411_rx_rp_ud(struct msgb *msg, struct gsm_trans *trans,
 		return gsm411_send_rp_ack(trans, rph->msg_ref);
 	else if (rc > 0)
 		return gsm411_send_rp_error(trans, rph->msg_ref, rc);
-	else
-		return rc;
+	else if (rc == -EINPROGRESS)
+		rc = 0;
+
+	return rc;
 }
 
 /* Receive a 04.11 RP-DATA message in accordance with Section 7.3.1.2 */
diff --git a/src/libmsc/smpp_openbsc.c b/src/libmsc/smpp_openbsc.c
index 98b3b5370..a79b2524c 100644
--- a/src/libmsc/smpp_openbsc.c
+++ b/src/libmsc/smpp_openbsc.c
@@ -773,6 +773,10 @@ static int deliver_to_esme(struct osmo_esme *esme, struct gsm_sms *sms,
 	if (ret < 0)
 		return ret;
 
+	OSMO_ASSERT(!sms->smpp.esme);
+	smpp_esme_get(esme);
+	sms->smpp.esme = esme;
+
 	return smpp_cmd_enqueue(esme, vsub, sms,
 				deliver.sequence_number);
 }