diff --git a/msc/BSC_ConnectionHandler.ttcn b/msc/BSC_ConnectionHandler.ttcn
index 7b88192..b041007 100644
--- a/msc/BSC_ConnectionHandler.ttcn
+++ b/msc/BSC_ConnectionHandler.ttcn
@@ -646,13 +646,18 @@
 	setverdict(pass);
 }
 
-function f_call_hangup(inout CallParameters cpars, boolean release_by_ms)
+function f_call_hangup(inout CallParameters cpars, boolean release_by_ms, boolean is_csfb := false)
 runs on BSC_ConnHdlr {
 
 	var MobileIdentityLV mi;
 	var MNCC_PDU mncc;
 	var MgcpCommand mgcp_cmd;
 	var boolean respond_to_dlcx;
+	var template PDU_BSSAP t_clear := tr_BSSMAP_ClearCommand;
+
+	if (is_csfb) {
+		t_clear := tr_BSSMAP_ClearCommandCSFB;
+	}
 
 	MNCC.send(ts_MNCC_DISC_req(cpars.mncc_callref, valueof(ts_MNCC_cause(23))));
 	BSSAP.receive(tr_PDU_DTAP_MT(tr_ML3_MT_CC_DISC(cpars.transaction_id)));
@@ -673,7 +678,7 @@
 
 	/* clearing of radio channel */
 	interleave {
-	[] BSSAP.receive(tr_BSSMAP_ClearCommand) {
+	[] BSSAP.receive(t_clear) {
 		BSSAP.send(ts_BSSMAP_ClearComplete);
 		BSSAP.receive(BSSAP_Conn_Prim:MSC_CONN_PRIM_DISC_IND);
 		}