diff --git a/include/osmocom/netif/osmux.h b/include/osmocom/netif/osmux.h
index 58ec40d..dd89973 100644
--- a/include/osmocom/netif/osmux.h
+++ b/include/osmocom/netif/osmux.h
@@ -49,8 +49,8 @@ struct osmux_in_handle {
 
 /* one per OSmux circuit_id, ie. one per RTP flow. */
 struct osmux_out_handle {
-	uint16_t rtp_seq;
-	uint32_t rtp_timestamp;
+	uint16_t rtp_seq[8];
+	uint32_t rtp_timestamp[8];
 };
 
 static inline uint8_t *osmux_get_payload(struct osmux_hdr *osmuxh)
@@ -65,6 +65,7 @@ void osmux_xfrm_input_register_ccid(struct osmux_in_handle *h, uint32_t ssrc);
 int osmux_xfrm_input(struct osmux_in_handle *h, struct msgb *msg);
 void osmux_xfrm_input_deliver(struct osmux_in_handle *h);
 
+void osmux_xfrm_output_init(struct osmux_out_handle *h);
 int osmux_xfrm_output(struct osmux_hdr *osmuxh, struct osmux_out_handle *h, struct llist_head *list);
 struct osmux_hdr *osmux_xfrm_output_pull(struct msgb *msg);
 
diff --git a/src/osmux.c b/src/osmux.c
index 508f01c..ad18c36 100644
--- a/src/osmux.c
+++ b/src/osmux.c
@@ -75,8 +75,8 @@ osmux_rebuild_rtp(struct osmux_out_handle *h,
 	rtph->version = RTP_VERSION;
 	rtph->payload_type = 98;
 	/* ... emulate timestamp and ssrc */
-	rtph->timestamp = htonl(h->rtp_timestamp);
-	rtph->sequence = htons(h->rtp_seq);
+	rtph->timestamp = htonl(h->rtp_timestamp[osmuxh->circuit_id]);
+	rtph->sequence = htons(h->rtp_seq[osmuxh->circuit_id]);
 	rtph->ssrc = htonl(ssrc_from_ccid);
 
 	msgb_put(out_msg, sizeof(struct rtp_hdr));
@@ -95,8 +95,8 @@ osmux_rebuild_rtp(struct osmux_out_handle *h,
 	msgb_put(out_msg, payload_len);
 
 	/* bump last RTP sequence number and timestamp that has been used */
-	h->rtp_seq++;
-	h->rtp_timestamp++;
+	h->rtp_seq[osmuxh->circuit_id]++;
+	h->rtp_timestamp[osmuxh->circuit_id]++;
 
 	osmo_rtp_snprintf(buf, sizeof(buf), out_msg);
 	LOGP(DOSMUX, LOGL_DEBUG, "%s\n", buf);
@@ -134,7 +134,7 @@ struct osmux_batch {
 	struct llist_head	msgb_list;
 	unsigned int		remaining_bytes;
 	uint8_t			seq;
-	int64_t			ccid[8];
+	int64_t			ccid[OSMUX_MAX_CONCURRENT_CALLS];
 };
 
 static int
@@ -507,3 +507,13 @@ int osmux_xfrm_input_get_ccid(struct osmux_in_handle *h, uint32_t ssrc)
 
 	return found ? i : -1;
 }
+
+void osmux_xfrm_output_init(struct osmux_out_handle *h)
+{
+	int i;
+
+	for (i=0; i<8; i++) {
+		h->rtp_seq[i] = (uint16_t)random();
+		h->rtp_timestamp[i] = (uint32_t)random();
+	}
+}
diff --git a/tests/osmo-pcap-test/osmux_test.c b/tests/osmo-pcap-test/osmux_test.c
index 8dab1bf..541665a 100644
--- a/tests/osmo-pcap-test/osmux_test.c
+++ b/tests/osmo-pcap-test/osmux_test.c
@@ -35,10 +35,7 @@
  * This is the output handle for osmux, it stores last RTP sequence and
  * timestamp that has been used. There should be one per circuit ID.
  */
-static struct osmux_out_handle h_output = {
-	.rtp_seq	= 1000,
-	.rtp_timestamp	= 10,
-};
+static struct osmux_out_handle h_output;
 
 static void tx_cb(struct msgb *msg, void *data)
 {
@@ -154,6 +151,7 @@ int main(int argc, char *argv[])
 	osmo_pcap.timer.cb = osmo_pcap_pkt_timer_cb;
 
 	osmux_xfrm_input_init(&h_input);
+	osmux_xfrm_output_init(&h_output);
 
 	/* first run */
 	osmo_pcap_pkt_timer_cb(NULL);