diff --git a/dia2gsup/DIA2GSUP_Tests.ttcn b/dia2gsup/DIA2GSUP_Tests.ttcn
index 6a3f85c..673038c 100644
--- a/dia2gsup/DIA2GSUP_Tests.ttcn
+++ b/dia2gsup/DIA2GSUP_Tests.ttcn
@@ -214,8 +214,145 @@
 	setverdict(pass);
 }
 
+private function f_DIA_AI_gsup_error(integer gsup_cause, template (present) GenericAVP err_avp) runs on D2G_ConnHdlr {
+	var PDU_DIAMETER rx_dia;
+	var UINT32 hbh_id := f_rnd_octstring(4);
+	var UINT32 ete_id := f_rnd_octstring(4);
+	var octetstring sess_id := char2oct("foobar");
+	var OCT3 vplmn := '00F110'O;
+
+	/* Unlike AIR, AIA contains no IMSI. Register ete_id in DIAMETER_Emulation,
+	 * so AIA is forwarded back to us in DIAMETER port instead of MTC_CT.DIAMETER_UNIT.
+	 */
+	f_diameter_expect_eteid(ete_id);
+
+	/* Send AIR to translator; expect it to show up on GSUP side */
+	DIAMETER.send(ts_DIA_AIR(g_pars.imsi, vplmn, sess_id, hbh_id := hbh_id, ete_id := ete_id));
+	GSUP.receive(tr_GSUP_SAI_REQ(g_pars.imsi));
+
+	/* Send an error response back to the translator; expect AIA */
+	GSUP.send(ts_GSUP_SAI_ERR(g_pars.imsi, gsup_cause));
+
+	alt {
+	/* Unlike AIR, AIA contains no IMSI, hence it is received in DIAMETER_UNIT: */
+	[] DIAMETER.receive(tr_DIA_AIA_ERR(err_avp)) {
+		setverdict(pass);
+		}
+	[] DIAMETER.receive(PDU_DIAMETER:?) -> value rx_dia {
+		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, log2str("Unexpected Diameter msg rx: ", rx_dia));
+		}
+	}
+}
+
+private function f_TC_authinfo_gsup_err_imsi_unknown(charstring id) runs on D2G_ConnHdlr {
+	var DIAMETER_ExperimentalResultcode res_code := DIAMETER_ERROR_USER_UNKNOWN;
+	f_DIA_AI_gsup_error(2, tr_AVP_ExperimentalResult(vendor_id_3GPP, int2oct(enum2int(res_code), 4)));
+}
+testcase TC_authinfo_gsup_err_imsi_unknown() runs on MTC_CT {
+	var D2G_ConnHdlrPars pars := f_init_pars();
+	var D2G_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_authinfo_gsup_err_imsi_unknown), pars);
+	vc_conn.done;
+	setverdict(pass);
+}
+
+private function f_TC_authinfo_gsup_err_illegal_ms(charstring id) runs on D2G_ConnHdlr {
+	var DIAMETER_ExperimentalResultcode res_code := DIAMETER_ERROR_USER_UNKNOWN;
+	f_DIA_AI_gsup_error(3, tr_AVP_ExperimentalResult(vendor_id_3GPP, int2oct(enum2int(res_code), 4)));
+}
+testcase TC_authinfo_gsup_err_illegal_ms() runs on MTC_CT {
+	var D2G_ConnHdlrPars pars := f_init_pars();
+	var D2G_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_authinfo_gsup_err_illegal_ms), pars);
+	vc_conn.done;
+	setverdict(pass);
+}
+
+private function f_TC_authinfo_gsup_err_plmn_not_allowed(charstring id) runs on D2G_ConnHdlr {
+	f_DIA_AI_gsup_error(11, tr_AVP_ResultCode(DIAMETER_UNABLE_TO_COMPLY));
+}
+testcase TC_authinfo_gsup_err_plmn_not_allowed() runs on MTC_CT {
+	var D2G_ConnHdlrPars pars := f_init_pars();
+	var D2G_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_authinfo_gsup_err_plmn_not_allowed), pars);
+	vc_conn.done;
+	setverdict(pass);
+}
+
+private function f_TC_authinfo_gsup_err_romaning_not_allowed(charstring id) runs on D2G_ConnHdlr {
+	var DIAMETER_ExperimentalResultcode res_code := DIAMETER_ERROR_ROAMING_NOT_ALLOWED;
+	f_DIA_AI_gsup_error(12, tr_AVP_ExperimentalResult(vendor_id_3GPP, int2oct(enum2int(res_code), 4)));
+}
+testcase TC_authinfo_gsup_err_romaning_not_allowed() runs on MTC_CT {
+	var D2G_ConnHdlrPars pars := f_init_pars();
+	var D2G_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_authinfo_gsup_err_romaning_not_allowed), pars);
+	vc_conn.done;
+	setverdict(pass);
+}
+
+private function f_TC_authinfo_gsup_err_net_fail(charstring id) runs on D2G_ConnHdlr {
+	f_DIA_AI_gsup_error(17, tr_AVP_ResultCode(DIAMETER_UNABLE_TO_COMPLY));
+}
+testcase TC_authinfo_gsup_err_net_fail() runs on MTC_CT {
+	var D2G_ConnHdlrPars pars := f_init_pars();
+	var D2G_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_authinfo_gsup_err_net_fail), pars);
+	vc_conn.done;
+	setverdict(pass);
+}
+
+private function f_TC_authinfo_gsup_err_congestion(charstring id) runs on D2G_ConnHdlr {
+	f_DIA_AI_gsup_error(22, tr_AVP_ResultCode(DIAMETER_UNABLE_TO_COMPLY));
+}
+testcase TC_authinfo_gsup_err_congestion() runs on MTC_CT {
+	var D2G_ConnHdlrPars pars := f_init_pars();
+	var D2G_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_authinfo_gsup_err_congestion), pars);
+	vc_conn.done;
+	setverdict(pass);
+}
+
+private function f_TC_authinfo_gsup_err_auth_unacceptable(charstring id) runs on D2G_ConnHdlr {
+	f_DIA_AI_gsup_error(23, tr_AVP_ResultCode(DIAMETER_UNABLE_TO_COMPLY));
+}
+testcase TC_authinfo_gsup_err_auth_unacceptable() runs on MTC_CT {
+	var D2G_ConnHdlrPars pars := f_init_pars();
+	var D2G_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_authinfo_gsup_err_auth_unacceptable), pars);
+	vc_conn.done;
+	setverdict(pass);
+}
+
+private function f_TC_authinfo_gsup_err_proto_unspec(charstring id) runs on D2G_ConnHdlr {
+	f_DIA_AI_gsup_error(23, tr_AVP_ResultCode(DIAMETER_UNABLE_TO_COMPLY));
+}
+testcase TC_authinfo_gsup_err_proto_unspec() runs on MTC_CT {
+	var D2G_ConnHdlrPars pars := f_init_pars();
+	var D2G_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_authinfo_gsup_err_proto_unspec), pars);
+	vc_conn.done;
+	setverdict(pass);
+}
+
 control {
 	execute ( TC_authinfo_normal() );
+	execute ( TC_authinfo_gsup_err_imsi_unknown() );
+	execute ( TC_authinfo_gsup_err_illegal_ms() );
+	execute ( TC_authinfo_gsup_err_plmn_not_allowed() );
+	execute ( TC_authinfo_gsup_err_romaning_not_allowed() );
+	execute ( TC_authinfo_gsup_err_net_fail() );
+	execute ( TC_authinfo_gsup_err_congestion() );
+	execute ( TC_authinfo_gsup_err_auth_unacceptable() );
+	execute ( TC_authinfo_gsup_err_proto_unspec() );
 }
 
 }
diff --git a/library/DIAMETER_Templates.ttcn b/library/DIAMETER_Templates.ttcn
index 63db7fc..8bb53e0 100644
--- a/library/DIAMETER_Templates.ttcn
+++ b/library/DIAMETER_Templates.ttcn
@@ -101,6 +101,22 @@
 	DIAMETER_ERROR_EAP_CODE_UNKNOWN			(5048)
 };
 
+/* 3GPP TS 29.272 section 7.4. Errors in Experimental-Result-Code */
+type enumerated DIAMETER_ExperimentalResultcode {
+	/* transient */
+	DIAMETER_AUTHENTICATION_DATA_UNAVAILABLE 	(4181),
+	DIAMETER_ERROR_CAMEL_SUBSCRIPTION_PRESENT 	(4182),
+	/* permanent */
+	DIAMETER_ERROR_USER_UNKNOWN			(5001),
+	DIAMETER_AUTHORIZATION_REJECTED			(5003),
+	DIAMETER_ERROR_ROAMING_NOT_ALLOWED		(5004),
+	DIAMETER_MISSING_AVP				(5005),
+	DIAMETER_ERROR_UNKNOWN_EPS_SUBSCRIPTION		(5420),
+	DIAMETER_ERROR_RAT_NOT_ALLOWED			(5421),
+	DIAMETER_ERROR_EQUIPMENT_UNKNOWN		(5422),
+	DIAMETER_ERROR_UNKOWN_SERVING_NODE		(5423)
+}
+
 /* Gy : 3GPP TS 32.299 7.1.6, RFC4006 3.1 */
 const uint32_t c_DIAMETER_CREDIT_CONTROL_AID := 4;
 /* 3GPP TS 29.272 Section 7.1.8 */
@@ -338,6 +354,24 @@
 		}
 	}
 }
+private function f_tr_AVP_VendorId(template (present) Vendor_Id vendor_id)
+return template (present) BASE_NONE_Vendor_Id {
+	if (istemplatekind(vendor_id, "?")) {
+		return ?;
+	} else {
+		var template (present) BASE_NONE_Vendor_Id c;
+		c := int2oct(enum2int(valueof(vendor_id)), 4);
+		return c;
+	}
+}
+template (present) GenericAVP tr_AVP_VendorId(template (present) Vendor_Id vendor_id) := {
+	avp := {
+		avp_header := tr_DIA_Hdr(c_AVP_Code_BASE_NONE_Vendor_Id),
+		avp_data := {
+			avp_BASE_NONE_Vendor_Id := f_tr_AVP_VendorId(vendor_id)
+		}
+	}
+}
 
 template (value) GenericAVP ts_AVP_ProductName(charstring name) := {
 	avp := {
@@ -451,6 +485,28 @@
 	}
 }
 
+template (present) GenericAVP tr_AVP_ExperimentalResultCode(template (present) AVP_Unsigned32 n := ?) := {
+	avp := {
+		avp_header := tr_DIA_Hdr(c_AVP_Code_BASE_NONE_Experimental_Result_Code),
+		avp_data := {
+			avp_BASE_NONE_Experimental_Result_Code := n
+		}
+	}
+}
+
+template (present) GenericAVP tr_AVP_ExperimentalResult(template (present) Vendor_Id vendor_id := ?,
+							template (present) AVP_Unsigned32 err_code := ?
+							) := {
+	avp := {
+		avp_header := tr_DIA_Hdr(c_AVP_Code_BASE_NONE_Experimental_Result),
+		avp_data := {
+			avp_BASE_NONE_Experimental_Result := {
+				tr_AVP_VendorId(vendor_id),
+				tr_AVP_ExperimentalResultCode(err_code)
+			}
+		}
+	}
+}
 
 template (value) GenericAVP ts_AVP_SuppVendorIdRaw(uint32_t vendor_id) := {
 	avp := {
@@ -471,11 +527,21 @@
 		}
 	}
 }
-template (present) GenericAVP tr_AVP_ResultCode(DIAMETER_Resultcode res_code) := {
+private function f_tr_DIAMETER_Resultcode(template (present) DIAMETER_Resultcode res_code)
+return template (present) BASE_NONE_Result_Code {
+	if (istemplatekind(res_code, "?")) {
+		return ?;
+	} else {
+		var template (present) BASE_NONE_Result_Code c;
+		c := int2oct(enum2int(valueof(res_code)), 4);
+		return c;
+	}
+}
+template (present) GenericAVP tr_AVP_ResultCode(template (present) DIAMETER_Resultcode res_code) := {
 	avp := {
 		avp_header := tr_DIA_Hdr(c_AVP_Code_BASE_NONE_Result_Code),
 		avp_data := {
-			avp_BASE_NONE_Result_Code := int2oct(enum2int(res_code), 4)
+			avp_BASE_NONE_Result_Code := f_tr_DIAMETER_Resultcode(res_code)
 		}
 	}
 }
@@ -1414,6 +1480,25 @@
 			tr_AVP_ResultCode(DIAMETER_SUCCESS),
 			tr_AVP_3GPP_AuthInfo(auth_info_contents)
 	));
+template (present) PDU_DIAMETER
+tr_DIA_AIA_ERR(template (present) GenericAVP err_avp := ?,
+	   template (present) octetstring sess_id := ?,
+	   template (present) charstring orig_host := ?,
+	   template (present) charstring orig_realm := ?,
+	   template (present) UINT32 hbh_id := ?,
+	   template (present) UINT32 ete_id := ?) :=
+	tr_DIAMETER(flags := '0???????'B,
+		    cmd_code := Authentication_Information,
+		    app_id := int2oct(c_DIAMETER_3GPP_S6_AID, 4),
+		    hbh_id := hbh_id,
+		    ete_id := ete_id,
+		    avps := superset(
+			tr_AVP_SessionId(sess_id),
+			tr_AVP_AuthSessionState(NO_STATE_MAINTAINED),
+			tr_AVP_OriginHost(orig_host),
+			tr_AVP_OriginRealm(orig_realm),
+			err_avp
+	));
 
 
 /* TS 29.272 7.2.3 Update Location Request */