diff --git a/library/GTPv2_Templates.ttcn b/library/GTPv2_Templates.ttcn
index e5022d8..753774d 100644
--- a/library/GTPv2_Templates.ttcn
+++ b/library/GTPv2_Templates.ttcn
@@ -740,38 +740,38 @@
 
 
 template (present) PDU_GTPCv2
-tr_GTP2C_CreateSessionReq(template (present) hexstring imsi) :=
+tr_GTP2C_CreateSessionReq(template (present) hexstring imsi := ?, template (present) octetstring apn := ?) :=
 tr_PDU_GTP2C('00000000'O, ?, {
 	createSessionRequest := {
 		iMSI := tr_GTP2C_Imsi(imsi),
 		mSISDN := *,
 		mEI := *,
-		userLocationInfo := ?,
-		servingNetwork := ?,
-		rAT_Type := tr_GTP2C_RatType(6),
+		userLocationInfo := *,
+		servingNetwork := *,
+		rAT_Type := tr_GTP2C_RatType(?),
 		indication := *,
 		fullyQualifiedTEID := ?,
-		accessPointName := tr_GTP2C_APN('012a'O), // '*'
+		accessPointName := tr_GTP2C_APN(apn), // '*'
 		selectionMode := ?,
-		pDN_Type := ?,
+		pDN_Type := *,
 		pDN_AddressAllocation := ?,
-		maxAPN_Restriction := ?,
+		maxAPN_Restriction := *,
 		ambr := *,
 		linkedEPS_Bearer_ID := omit,
 		trustedWLANModeIndication := omit,
 		protocolConfigOptions := omit,
 		bearerContextGrouped := ?,
 		traceInformation := *,
-		recovery := omit,
+		recovery := *,
 		csid := omit,
-		uE_TimeZone := ?,
+		uE_TimeZone := *,
 		user_CSG_Information := omit,
-		chargingCharacteristics := ?,
+		chargingCharacteristics := *,
 		lDN := omit,
 		signallingPriorityIndication := *,
 		iP_Addr := omit,
 		portNumber := omit,
-		aPCO := omit,
+		aPCO := *,
 		trustedWLANAccessNetworkIdentifier := omit,
 		cNOperatorSelectionEntity := omit,
 		presenceReportingAreaInformation := omit,