diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index a74b3fe..162bfe6 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -3729,7 +3729,12 @@
 }
 
 /* Send UI frame from MS and expect it to arrive as RLL UNITDATA IND on Abis */
-function f_unitdata_mo(RslLinkId link_id, octetstring l3) runs on ConnHdlr {
+function f_unitdata_mo(
+	RslLinkId link_id,
+	octetstring l3,
+	boolean exp_sacch := true, /* Should tolerate SACCH messages? */
+	boolean exp_any := true /* Should tolerate any other RSL messages? */
+) runs on ConnHdlr {
 	timer T := 3.0;
 	f_tx_lapdm(ts_LAPDm_UI(link_id.sapi, cr_MO_CMD, l3), link_id);
 	T.start;
@@ -3738,11 +3743,22 @@
 	[] RSL.receive(tr_RSL_UNITDATA_IND(g_chan_nr, link_id, l3)) {
 		setverdict(pass);
 		}
+	/* Expect (or not expect) SACCH messages (Measurement Reports) */
+	[exp_sacch] RSL.receive(tr_RSL_UNITDATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) { repeat; }
+	[not exp_sacch] RSL.receive(tr_RSL_UNITDATA_IND(g_chan_nr, tr_RslLinkID_SACCH(?))) {
+		setverdict(fail, "Unexpected (SACCH) UNIT_DATA_IND message!");
+		mtc.stop;
+		}
+	/* Expect (or not expect) other kinds of messages */
+	[exp_any] RSL.receive { repeat; }
+	[not exp_any] RSL.receive {
+		setverdict(fail, "Unexpected RSL message!");
+		mtc.stop;
+		}
 	[] T.timeout {
 		setverdict(fail, "Timeout waiting for UNIT_DATA_IND");
 		mtc.stop;
 		}
-	[] RSL.receive { repeat; }
 	}
 }