diff --git a/include/osmocom/trau/osmo_ortp.h b/include/osmocom/trau/osmo_ortp.h
index 9eb176f..578b1cb 100644
--- a/include/osmocom/trau/osmo_ortp.h
+++ b/include/osmocom/trau/osmo_ortp.h
@@ -76,6 +76,7 @@
 int osmo_rtp_socket_connect(struct osmo_rtp_socket *rs, const char *ip, uint16_t port);
 int osmo_rtp_socket_set_pt(struct osmo_rtp_socket *rs, int payload_type);
 int osmo_rtp_socket_free(struct osmo_rtp_socket *rs);
+int osmo_rtp_skipped_frame(struct osmo_rtp_socket *rs, unsigned int duration);
 int osmo_rtp_send_frame(struct osmo_rtp_socket *rs, const uint8_t *payload,
 			unsigned int payload_len, unsigned int duration);
 int osmo_rtp_send_frame_ext(struct osmo_rtp_socket *rs, const uint8_t *payload,