diff --git a/openbsc/src/input/dahdi.c b/openbsc/src/input/dahdi.c
index 08bd1e0..c086954 100644
--- a/openbsc/src/input/dahdi.c
+++ b/openbsc/src/input/dahdi.c
@@ -169,7 +169,8 @@
 		return 0;
 	}
 
-	lapd_transmit(e1i_ts->driver.dahdi.lapd, sign_link->tei, msg->data, msg->len);
+	lapd_transmit(e1i_ts->driver.dahdi.lapd, sign_link->tei,
+		      sign_link->sapi, msg->data, msg->len);
 	msgb_free(msg);
 
 	/* set tx delay timer for next event */