diff --git a/bsc-nat/BSC_MS_ConnectionHandler.ttcn b/bsc-nat/BSC_MS_ConnectionHandler.ttcn
index 6efb15b..1f41434 100644
--- a/bsc-nat/BSC_MS_ConnectionHandler.ttcn
+++ b/bsc-nat/BSC_MS_ConnectionHandler.ttcn
@@ -58,7 +58,7 @@
 
 function f_gen_cl3(hexstring imsi) return PDU_BSSAP {
 	var MobileIdentityLV mi := valueof(ts_MI_IMSI_LV(imsi));
-	var PDU_ML3_MS_NW l3 := valueof(ts_CM_SERV_REQ('0001'B, mi));
+	var PDU_ML3_MS_NW l3 := valueof(ts_CM_SERV_REQ(CM_TYPE_MO_CALL, mi));
 	var BSSMAP_IE_CellIdentifier cell_id := valueof(ts_CellID_LAC_CI(23, 42));
 	var PDU_BSSAP bssap := valueof(ts_BSSMAP_ComplL3(cell_id, enc_PDU_ML3_MS_NW(l3)));
 	return bssap;