diff --git a/epdg/EPDG_Tests.ttcn b/epdg/EPDG_Tests.ttcn
index d8112e8d5..31963f44e 100644
--- a/epdg/EPDG_Tests.ttcn
+++ b/epdg/EPDG_Tests.ttcn
@@ -19,6 +19,7 @@ import from GSUP_Emulation all;
 import from DIAMETER_Types all;
 import from DIAMETER_Templates all;
 import from DIAMETER_rfc4004_Templates all;
+import from DIAMETER_ts29_229_Templates all;
 import from DIAMETER_ts29_272_Templates all;
 import from DIAMETER_ts29_273_Templates all;
 import from DIAMETER_Emulation all;
@@ -470,6 +471,32 @@ private altstep as_DIA_SWx_SA_success(template (present) CxDx_3GPP_Server_Assign
 	}
 }
 
+/* Send RTR as HSS to AAA server, expect back RTA */
+private function f_DIA_SWx_RT(template (value) CxDx_3GPP_Reason_Code reason_code,
+			      template (present) GenericAVP exp_result_tmpl := tr_AVP_ResultCode(DIAMETER_SUCCESS)) runs on EPDG_ConnHdlr {
+	var PDU_DIAMETER rx_dia;
+	var UINT32 hbh_id := f_rnd_octstring(4);
+	var UINT32 ete_id := f_rnd_octstring(4);
+	var octetstring reason_info := char2oct("test");
+
+	/* Unlike STR, STA 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_epdg_connhldr_SWx_expect_eteid(ete_id);
+
+	SWx.send(ts_DIA_SWx_RTR(g_pars.imsi, reason_code, reason_info,
+				hbh_id := hbh_id,
+				ete_id := ete_id));
+
+	alt {
+	[] SWx.receive(tr_DIA_SWx_RTA(exp_result_tmpl, hbh_id := hbh_id, ete_id := ete_id)) -> value rx_dia {}
+	[] SWx.receive(PDU_DIAMETER:?) -> value rx_dia {
+		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, log2str("Unexpected Diameter SWx msg rx: ", rx_dia));
+		}
+	}
+}
+
+
 /* Send AAR as PGW to AAA server, expect back AAA */
 private function f_S6b_AA_success() runs on EPDG_ConnHdlr {
 	var PDU_DIAMETER rx_dia;
@@ -1025,6 +1052,24 @@ testcase TC_s2b_CreateSession_rejected() runs on MTC_CT {
 	setverdict(pass);
 }
 
+/* 3GPP TS 29.273 Network Initiated De-Registration by HSS, Administrative */
+private function f_TC_hss_initiated_deregister_new_server_assigned(charstring id) runs on EPDG_ConnHdlr {
+	f_initial_attach();
+	/* Procedure should be performed properly: */
+	f_DIA_SWx_RT(NEW_SERVER_ASSIGNED, tr_AVP_ResultCode(DIAMETER_SUCCESS));
+	/* Subscriber was already removed, it should fail if requested again: */
+	var DIAMETER_ts29_229_ExperimentalResultcode erc := DIAMETER_ERROR_USER_UNKNOWN;
+	f_DIA_SWx_RT(NEW_SERVER_ASSIGNED, tr_AVP_ExperimentalResult(vendor_id_3GPP, int2oct(enum2int(erc), 4)));
+}
+testcase TC_hss_initiated_deregister_new_server_assigned() runs on MTC_CT {
+	var EPDG_ConnHdlrPars pars := f_init_pars();
+	var EPDG_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_hss_initiated_deregister_new_server_assigned), pars);
+	vc_conn.done;
+	setverdict(pass);
+}
+
 private function f_TC_concurrent_ues(charstring id) runs on EPDG_ConnHdlr {
 	COORD.send(COORD_CMD_READY);
 	COORD.receive(COORD_CMD_START);
@@ -1121,6 +1166,7 @@ control {
 	execute ( TC_ho_lte_to_wifi() );
 	execute ( TC_ho_wifi_to_lte() );
 	execute ( TC_s2b_CreateSession_rejected() );
+	execute ( TC_hss_initiated_deregister_new_server_assigned() );
 	execute ( TC_concurrent_ues2() );
 	execute ( TC_concurrent_ues100() );
 	execute ( TC_upf_echo_req() );
diff --git a/epdg/expected-results.xml b/epdg/expected-results.xml
index 6507cc2d8..bb288119d 100644
--- a/epdg/expected-results.xml
+++ b/epdg/expected-results.xml
@@ -7,6 +7,7 @@
   <testcase classname='EPDG_Tests' name='TC_ho_lte_to_wifi' time='MASKED'/>
   <testcase classname='EPDG_Tests' name='TC_ho_wifi_to_lte' time='MASKED'/>
   <testcase classname='EPDG_Tests' name='TC_s2b_CreateSession_rejected' time='MASKED'/>
+  <testcase classname='EPDG_Tests' name='TC_hss_initiated_deregister_new_server_assigned' time='MASKED'/>
   <testcase classname='EPDG_Tests' name='TC_concurrent_ues2' time='MASKED'/>
   <testcase classname='EPDG_Tests' name='TC_concurrent_ues100' time='MASKED'/>
   <testcase classname='EPDG_Tests' name='TC_upf_echo_req' time='MASKED'/>
diff --git a/epdg/gen_links.sh b/epdg/gen_links.sh
index f0b2f5c9d..55e449f0e 100755
--- a/epdg/gen_links.sh
+++ b/epdg/gen_links.sh
@@ -55,7 +55,7 @@ FILES+="Osmocom_CTRL_Types.ttcn "
 FILES+="L3_Common.ttcn "
 FILES+="DNS_Helpers.ttcn "
 FILES+="DIAMETER_Types.ttcn DIAMETER_CodecPort.ttcn DIAMETER_CodecPort_CtrlFunct.ttcn DIAMETER_CodecPort_CtrlFunctDef.cc DIAMETER_Emulation.ttcn "
-FILES+="DIAMETER_Templates.ttcn DIAMETER_rfc4004_Templates.ttcn DIAMETER_rfc5447_Templates.ttcn DIAMETER_ts29_272_Templates.ttcn DIAMETER_ts29_273_Templates.ttcn "
+FILES+="DIAMETER_Templates.ttcn DIAMETER_rfc4004_Templates.ttcn DIAMETER_rfc5447_Templates.ttcn DIAMETER_ts29_229_Templates.ttcn DIAMETER_ts29_272_Templates.ttcn DIAMETER_ts29_273_Templates.ttcn "
 FILES+="IPA_Types.ttcn IPA_CodecPort.ttcn IPA_CodecPort_CtrlFunct.ttcn IPA_CodecPort_CtrlFunctDef.cc
 IPA_Emulation.ttcnpp "
 FILES+="PCO_Types.ttcn GSUP_Types.ttcn GSUP_Templates.ttcn GSUP_Emulation.ttcn "
diff --git a/library/DIAMETER_Templates.ttcn b/library/DIAMETER_Templates.ttcn
index 338899f38..31ea8216f 100644
--- a/library/DIAMETER_Templates.ttcn
+++ b/library/DIAMETER_Templates.ttcn
@@ -682,7 +682,7 @@ template (present) GenericAVP tr_AVP_UserName(template (present) octetstring uid
 		}
 	}
 }
-template (value) GenericAVP ts_AVP_UserNameImsi(hexstring imsi) := ts_AVP_UserName(char2oct(hex2str(imsi)));
+template (value) GenericAVP ts_AVP_UserNameImsi(template (value) hexstring imsi) := ts_AVP_UserName(char2oct(hex2str(valueof(imsi))));
 template (present) GenericAVP tr_AVP_UserNameImsi(template (present) hexstring imsi := ?) := tr_AVP_UserName(char2oct_tmpl(hex2str_tmpl(imsi)));
 
 
diff --git a/library/DIAMETER_ts29_229_Templates.ttcn b/library/DIAMETER_ts29_229_Templates.ttcn
new file mode 100644
index 000000000..bab9bd9c3
--- /dev/null
+++ b/library/DIAMETER_ts29_229_Templates.ttcn
@@ -0,0 +1,78 @@
+module DIAMETER_ts29_229_Templates {
+
+/* (C) 2023 by sysmocom s.f.m.c. GmbH <info@sysmocom.de
+ * All rights reserved.
+ *
+ * Released under the terms of GNU General Public License, Version 2 or
+ * (at your option) any later version.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * Templates for AVPs and messages for TS 29.273
+ */
+
+import from General_Types all;
+import from DIAMETER_Types all;
+import from DIAMETER_Templates all;
+import from DIAMETER_rfc5447_Templates all;
+import from DIAMETER_ts29_272_Templates all;
+import from Osmocom_Types all;
+import from Misc_Helpers all;
+
+/* 3GPP TS 29.229 section 6.2. Errors in Result-Code AVP values */
+type enumerated DIAMETER_ts29_229_ExperimentalResultcode {
+	/* Success */
+	DIAMETER_FIRST_REGISTRATION 		(2001),
+	DIAMETER_SUBSEQUENT_REGISTRATION 	(2002),
+	DIAMETER_UNREGISTERED_SERVICE 	 	(2003),
+	DIAMETER_SUCCESS_SERVER_NAME_NOT_STORED (2004),
+	/* Permanent Failures */
+	DIAMETER_ERROR_USER_UNKNOWN			(5001),
+	DIAMETER_ERROR_IDENTITIES_DONT_MATCH		(5002),
+	DIAMETER_ERROR_IDENTITY_NOT_REGISTERED		(5003),
+	DIAMETER_ERROR_ROAMING_NOT_ALLOWED		(5004),
+	DIAMETER_ERROR_IDENTITY_ALREADY_REGISTERED	(5005),
+	DIAMETER_ERROR_AUTH_SCHEME_NOT_SUPPORTED	(5006),
+	DIAMETER_ERROR_IN_ASSIGNMENT_TYPE		(5007),
+	DIAMETER_ERROR_TOO_MUCH_DATA			(5008),
+	DIAMETER_ERROR_NOT_SUPPORTED_USER_DATA		(5009),
+	DIAMETER_ERROR_FEATURE_UNSUPPORTED		(5011),
+	DIAMETER_ERROR_SERVING_NODE_FEATURE_UNSUPPORTED	(5012)
+}
+
+/* TS 29.229 6.3.16 Deregistration-Reason */
+template (value) GenericAVP ts_AVP_CxDx_3GPP_Deregistration_Reason(template (value) CxDx_3GPP_Reason_Code reason,
+                                                                   template (value) octetstring info) := {
+	avp := {
+		avp_header := ts_DIA_Hdr_3GPP(c_AVP_Code_AAA_3GPP_Non_3GPP_User_Data),
+		avp_data := {
+			avp_CxDx_3GPP_Deregistration_Reason := {
+				ts_AVP_CxDx_3GPP_Reason_Code(reason),
+				ts_AVP_CxDx_3GPP_Reason_Info(info)
+			}
+		}
+	}
+}
+
+/* TS 29.229 6.3.17 Reason-Code AVP */
+template (value) GenericAVP ts_AVP_CxDx_3GPP_Reason_Code(template (value) CxDx_3GPP_Reason_Code reason) := {
+	avp := {
+		avp_header := ts_DIA_Hdr_3GPP(c_AVP_Code_CxDx_3GPP_Reason_Code),
+		avp_data := {
+			avp_CxDx_3GPP_Reason_Code := reason
+		}
+	}
+}
+
+
+/* 6.3.18 Reason-Info AVP */
+template (value) GenericAVP ts_AVP_CxDx_3GPP_Reason_Info(template (value) octetstring info) := {
+	avp := {
+		avp_header := ts_DIA_Hdr_3GPP(c_AVP_Code_CxDx_3GPP_Reason_Info),
+		avp_data := {
+			avp_CxDx_3GPP_Reason_Info := info
+		}
+	}
+}
+
+}
diff --git a/library/DIAMETER_ts29_273_Templates.ttcn b/library/DIAMETER_ts29_273_Templates.ttcn
index f0ac442a1..0a42d6a62 100644
--- a/library/DIAMETER_ts29_273_Templates.ttcn
+++ b/library/DIAMETER_ts29_273_Templates.ttcn
@@ -15,6 +15,7 @@ import from General_Types all;
 import from DIAMETER_Types all;
 import from DIAMETER_Templates all;
 import from DIAMETER_rfc5447_Templates all;
+import from DIAMETER_ts29_229_Templates all;
 import from DIAMETER_ts29_272_Templates all;
 import from Osmocom_Types all;
 import from Misc_Helpers all;
@@ -269,6 +270,61 @@ ts_DIA_SWx_SAA(template (value) hexstring imsi,
 			 */
 	});
 
+/* Registration-Termination-Request (RTR) , 8.2.2.4 Network Initiated De-Registration by HSS Procedure */
+template (value) PDU_DIAMETER
+ts_DIA_SWx_RTR(template (value) hexstring imsi,
+	       template (value) CxDx_3GPP_Reason_Code reason_code := PERMANENT_TERMINATION,
+               template (value) octetstring reason_info := ''O,
+	       template (value) uint32_t vendor_app_id := c_DIAMETER_3GPP_SWx_AID,
+	       template (value) octetstring sess_id := c_def_sess_id,
+	       template (value) charstring orig_host := "hss.localdomain",
+	       template (value) charstring orig_realm := "localdomain",
+	       template (value) charstring dest_host := "aaa.localdomain",
+	       template (value) charstring dest_realm := "localdomain",
+	       template (value) UINT32 hbh_id := '00000000'O,
+	       template (value) UINT32 ete_id := '00000000'O) :=
+	ts_DIAMETER(flags := '11000000'B,
+		    cmd_code := Registration_Termination,
+		    app_id := int2oct(c_DIAMETER_3GPP_SWx_AID, 4),
+		    hbh_id := hbh_id,
+		    ete_id := ete_id,
+		    avps := {
+			ts_AVP_SessionId(sess_id),
+			ts_AVP_VendorSpecAppId(vendor_id_3GPP, valueof(vendor_app_id)),
+			ts_AVP_AuthSessionState(NO_STATE_MAINTAINED),
+			ts_AVP_OriginHost(orig_host),
+			ts_AVP_OriginRealm(orig_realm),
+			ts_AVP_DestinationHost(dest_host),
+			ts_AVP_DestinationRealm(dest_realm),
+			ts_AVP_UserNameImsi(imsi),
+			ts_AVP_CxDx_3GPP_Deregistration_Reason(reason_code, reason_info)
+			/* TODO:
+			 * *[ Supported-Features ]
+			 */
+	});
+
+template (present) PDU_DIAMETER
+tr_DIA_SWx_RTA(template (present) GenericAVP tmpl_result := ?,
+	       template (present) octetstring sess_id := ?,
+	       template (present) charstring orig_host :=  ?,
+	       template (present) charstring orig_realm := ?,
+	       template (present) charstring dest_host := ?,
+	       template (present) charstring dest_realm := ?,
+	       template (present) UINT32 hbh_id := ?,
+	       template (present) UINT32 ete_id := ?) :=
+	tr_DIAMETER(flags := '0???????'B,
+		    cmd_code := Registration_Termination,
+		    app_id := int2oct(c_DIAMETER_3GPP_SWx_AID, 4),
+		    hbh_id := hbh_id, ete_id := ete_id,
+		    avps := superset(
+			tr_AVP_SessionId(sess_id),
+			tr_AVP_VendorSpecAppId(?, ?),
+			tmpl_result,
+			tr_AVP_AuthSessionState(NO_STATE_MAINTAINED),
+			tr_AVP_OriginHost(orig_host),
+			tr_AVP_OriginRealm(orig_realm)
+	));
+
 /*******************************
  * S6b 3GPP TS 29.273 section 9
  *******************************/
diff --git a/pgw/gen_links.sh b/pgw/gen_links.sh
index 70494cec5..9bdface5c 100755
--- a/pgw/gen_links.sh
+++ b/pgw/gen_links.sh
@@ -64,7 +64,7 @@ FILES+="GTPv2_PrivateExtensions.ttcn GTPv2_Templates.ttcn "
 FILES+="GTPv2_CodecPort.ttcn GTPv2_CodecPort_CtrlFunctDef.cc GTPv2_CodecPort_CtrlFunct.ttcn GTPv2_Emulation.ttcn "
 FILES+="DNS_Helpers.ttcn "
 FILES+="DIAMETER_Types.ttcn DIAMETER_CodecPort.ttcn DIAMETER_CodecPort_CtrlFunct.ttcn DIAMETER_CodecPort_CtrlFunctDef.cc DIAMETER_Emulation.ttcn "
-FILES+="DIAMETER_Templates.ttcn DIAMETER_rfc4004_Templates.ttcn DIAMETER_rfc5447_Templates.ttcn DIAMETER_ts29_212_Templates.ttcn DIAMETER_ts29_272_Templates.ttcn DIAMETER_ts29_273_Templates.ttcn DIAMETER_ts32_299_Templates.ttcn "
+FILES+="DIAMETER_Templates.ttcn DIAMETER_rfc4004_Templates.ttcn DIAMETER_rfc5447_Templates.ttcn DIAMETER_ts29_212_Templates.ttcn DIAMETER_ts29_212_Templates.ttcn DIAMETER_ts29_229_Templates.ttcn DIAMETER_ts29_272_Templates.ttcn DIAMETER_ts29_273_Templates.ttcn DIAMETER_ts32_299_Templates.ttcn "
 gen_links $DIR $FILES
 
 ignore_pp_results