diff --git a/bts/BTS_Tests_ASCI.ttcn b/bts/BTS_Tests_ASCI.ttcn
index 315b67f..6814295 100644
--- a/bts/BTS_Tests_ASCI.ttcn
+++ b/bts/BTS_Tests_ASCI.ttcn
@@ -333,11 +333,90 @@
 	Misc_Helpers.f_shutdown(__BFILE__, __LINE__);
 }
 
+private function f_TC_vgcs_listener_det(charstring id) runs on ConnHdlr
+{
+	var octetstring uplink_access := '25'O;
+	var RSL_Message rm;
+	var GsmFrameNumber fn;
+
+	f_l1_tune(L1CTL);
+	RSL.clear;
+
+	/* Activate channel on the BTS side. */
+	log("Activating VGCS channel.");
+	f_rsl_chan_act(g_pars.chan_mode);
+
+	/* Enable dedicated mode. */
+	f_l1ctl_est_dchan(L1CTL, g_pars);
+
+	/* Send UPLINK ACCESS on VGCS channel. */
+	log("Send UPLINK ACCESS.");
+	fn := f_L1CTL_RACH(L1CTL, oct2int(uplink_access), chan_nr := g_pars.chan_nr);
+
+	/* Wait for listener detection. */
+	timer T := 2.0;
+	T.start;
+	alt {
+	[] RSL.receive(tr_RSL_LISTENER_DET(g_pars.chan_nr, ?)) -> value rm {
+		log("RSL Talker Listener has been detected: ", rm);
+		T.stop;
+		}
+	[] RSL.receive(tr_RSL_CHAN_RQD(?, ?, ?, ?)) -> value rm {
+		setverdict(fail, "RSL_CHAN_RQD was not expected: ", rm);
+		T.stop;
+		}
+	[] RSL.receive { repeat; }
+	[] T.timeout {
+		setverdict(fail, "Timeout waiting for RSL Listener Detect.");
+		}
+	}
+
+	/* Send UPLINK ACCESS on VGCS channel. */
+	log("Send second UPLINK ACCESS.");
+	fn := f_L1CTL_RACH(L1CTL, oct2int(uplink_access), chan_nr := g_pars.chan_nr);
+
+	/* Wait for listener detection. */
+	T.start;
+	alt {
+	[] RSL.receive(tr_RSL_LISTENER_DET(g_pars.chan_nr, ?)) {
+		setverdict(fail, "RSL Listener Detect has been detected, but not expected!");
+		T.stop;
+		}
+	[] RSL.receive(tr_RSL_CHAN_RQD(?, ?, ?, ?)) -> value rm {
+		setverdict(fail, "RSL_CHAN_RQD was not expected: ", rm);
+		T.stop;
+		}
+	[] RSL.receive { repeat; }
+	[] T.timeout {
+		log("Timeout waiting for RSL Listener Detect, as expected.");
+		}
+	}
+
+	/* Deactivate and cleanup. */
+	f_vgcs_cleanup();
+}
+testcase TC_vgcs_listener_det() runs on test_CT
+{
+	var template RSL_IE_ChannelMode ch_mode;
+	var ConnHdlrPars pars;
+	var ConnHdlr vc_conn;
+
+	f_init();
+
+	ch_mode := ts_RSL_ChanMode(RSL_CHRT_TCH_F_GROUP, RSL_CMOD_SP_GSM1);
+	pars := valueof(t_Pars(t_RslChanNr_Bm(1), ch_mode));
+	vc_conn := f_start_handler(refers(f_TC_vgcs_listener_det), pars);
+	vc_conn.done;
+
+	Misc_Helpers.f_shutdown(__BFILE__, __LINE__);
+}
+
 control {
 	execute( TC_vbs_notification() );
 	execute( TC_vgcs_uplink_free_and_busy() );
 	execute( TC_vgcs_talker_fail() );
 	execute( TC_vgcs_talker_est_rel() );
+	execute( TC_vgcs_listener_det() );
 
 }