diff --git a/lib/sbi/custom/patch_item.c b/lib/sbi/custom/patch_item.c
index 533b55bf0..a502b338e 100644
--- a/lib/sbi/custom/patch_item.c
+++ b/lib/sbi/custom/patch_item.c
@@ -76,7 +76,7 @@ cJSON *OpenAPI_patch_item_convertToJSON(OpenAPI_patch_item_t *patch_item)
             }
         } else if (OpenAPI_IsBool(patch_item->value)) {
             if (cJSON_AddBoolToObject(
-                    item, "value", OpenAPI_IsTrue(patch_item->value))) {
+                    item, "value", OpenAPI_IsTrue(patch_item->value)) == NULL) {
                 ogs_error("OpenAPI_patch_item_convertToJSON() failed [value]");
                 goto end;
             }
diff --git a/lib/sbi/message.c b/lib/sbi/message.c
index 306058af5..e67c8c94f 100644
--- a/lib/sbi/message.c
+++ b/lib/sbi/message.c
@@ -100,6 +100,9 @@ void ogs_sbi_message_free(ogs_sbi_message_t *message)
     if (message->Amf3GppAccessRegistration)
         OpenAPI_amf3_gpp_access_registration_free(
                 message->Amf3GppAccessRegistration);
+    if (message->Amf3GppAccessRegistrationModification)
+        OpenAPI_amf3_gpp_access_registration_modification_free(
+                message->Amf3GppAccessRegistrationModification);
     if (message->AccessAndMobilitySubscriptionData)
         OpenAPI_access_and_mobility_subscription_data_free(
                 message->AccessAndMobilitySubscriptionData);
@@ -760,6 +763,10 @@ static char *build_json(ogs_sbi_message_t *message)
         item = OpenAPI_amf3_gpp_access_registration_convertToJSON(
                 message->Amf3GppAccessRegistration);
         ogs_assert(item);
+    } else if (message->Amf3GppAccessRegistrationModification) {
+        item = OpenAPI_amf3_gpp_access_registration_modification_convertToJSON(
+                message->Amf3GppAccessRegistrationModification);
+        ogs_assert(item);
     } else if (message->AccessAndMobilitySubscriptionData) {
         item = OpenAPI_access_and_mobility_subscription_data_convertToJSON(
                 message->AccessAndMobilitySubscriptionData);
@@ -1098,13 +1105,30 @@ static int parse_json(ogs_sbi_message_t *message,
             CASE(OGS_SBI_RESOURCE_NAME_REGISTRATIONS)
                 SWITCH(message->h.resource.component[2])
                 CASE(OGS_SBI_RESOURCE_NAME_AMF_3GPP_ACCESS)
-                    message->Amf3GppAccessRegistration =
-                        OpenAPI_amf3_gpp_access_registration_parseFromJSON(
-                                item);
-                    if (!message->Amf3GppAccessRegistration) {
-                        rv = OGS_ERROR;
-                        ogs_error("JSON parse error");
-                    }
+
+                    SWITCH(message->h.method)
+                        CASE(OGS_SBI_HTTP_METHOD_PUT)
+                            message->Amf3GppAccessRegistration =
+                                OpenAPI_amf3_gpp_access_registration_parseFromJSON(
+                                        item);
+                            if (!message->Amf3GppAccessRegistration) {
+                                rv = OGS_ERROR;
+                                ogs_error("JSON parse error");
+                            }
+                            break;
+                        CASE(OGS_SBI_HTTP_METHOD_PATCH)
+                            message->Amf3GppAccessRegistrationModification =
+                                OpenAPI_amf3_gpp_access_registration_modification_parseFromJSON(
+                                        item);
+                            if (!message->Amf3GppAccessRegistrationModification) {
+                                rv = OGS_ERROR;
+                                ogs_error("JSON parse error");
+                            }
+                            break;
+                        DEFAULT
+                            rv = OGS_ERROR;
+                            ogs_error("Unknown method [%s]", message->h.method);
+                        END
                     break;
                 DEFAULT
                     rv = OGS_ERROR;
diff --git a/lib/sbi/message.h b/lib/sbi/message.h
index e3b3f0c9e..ee3b7eaf6 100644
--- a/lib/sbi/message.h
+++ b/lib/sbi/message.h
@@ -373,6 +373,8 @@ typedef struct ogs_sbi_message_s {
     OpenAPI_confirmation_data_response_t *ConfirmationDataResponse;
     OpenAPI_auth_event_t *AuthEvent;
     OpenAPI_amf3_gpp_access_registration_t *Amf3GppAccessRegistration;
+    OpenAPI_amf3_gpp_access_registration_modification_t
+        *Amf3GppAccessRegistrationModification;
     OpenAPI_access_and_mobility_subscription_data_t
         *AccessAndMobilitySubscriptionData;
     OpenAPI_smf_selection_subscription_data_t *SmfSelectionSubscriptionData;
diff --git a/lib/sbi/ogs-sbi.h b/lib/sbi/ogs-sbi.h
index 454df7d16..c0400a30e 100644
--- a/lib/sbi/ogs-sbi.h
+++ b/lib/sbi/ogs-sbi.h
@@ -42,6 +42,7 @@
 #include "model/confirmation_data_response.h"
 #include "model/auth_event.h"
 #include "model/amf3_gpp_access_registration.h"
+#include "model/amf3_gpp_access_registration_modification.h"
 #include "model/access_and_mobility_subscription_data.h"
 #include "model/smf_selection_subscription_data.h"
 #include "model/ue_context_in_smf_data.h"
diff --git a/src/amf/gmm-sm.c b/src/amf/gmm-sm.c
index 9145f9798..95cf86da5 100644
--- a/src/amf/gmm-sm.c
+++ b/src/amf/gmm-sm.c
@@ -450,6 +450,39 @@ static void common_register_state(ogs_fsm_t *s, amf_event_t *e)
             END
             break;
 
+        CASE(OGS_SBI_SERVICE_NAME_NUDM_UECM)
+            SWITCH(sbi_message->h.resource.component[1])
+            CASE(OGS_SBI_RESOURCE_NAME_REGISTRATIONS)
+                SWITCH(sbi_message->h.resource.component[2])
+                CASE(OGS_SBI_RESOURCE_NAME_AMF_3GPP_ACCESS)
+                    SWITCH(sbi_message->h.method)
+                    CASE(OGS_SBI_HTTP_METHOD_PATCH)
+
+                        ogs_assert(true ==
+                            amf_ue_sbi_discover_and_send(
+                                OpenAPI_nf_type_PCF, amf_ue,
+                                NULL, amf_npcf_am_policy_control_build_delete));
+
+                        break;
+
+                    DEFAULT
+                        ogs_error("Unknown method [%s]", sbi_message->h.method);
+                        ogs_assert_if_reached();
+                    END
+                    break;
+                DEFAULT
+                    ogs_error("Invalid resource name [%s]",
+                            sbi_message->h.resource.component[2]);
+                    ogs_assert_if_reached();
+                END
+                break;
+
+            DEFAULT
+                ogs_error("Invalid resource name [%s]",
+                        sbi_message->h.resource.component[1]);
+                ogs_assert_if_reached();
+            END
+            break;
         DEFAULT
             ogs_error("Invalid service name [%s]", sbi_message->h.service.name);
             ogs_assert_if_reached();
diff --git a/src/amf/nsmf-handler.c b/src/amf/nsmf-handler.c
index 2953c4b46..7d47ccf77 100644
--- a/src/amf/nsmf-handler.c
+++ b/src/amf/nsmf-handler.c
@@ -886,8 +886,8 @@ int amf_nsmf_pdusession_handle_release_sm_context(amf_sess_t *sess, int state)
 
                     ogs_assert(true ==
                         amf_ue_sbi_discover_and_send(
-                            OpenAPI_nf_type_PCF, amf_ue,
-                            NULL, amf_npcf_am_policy_control_build_delete));
+                            OpenAPI_nf_type_UDM, amf_ue,
+                            NULL, amf_nudm_uecm_build_registration_delete));
 
                 } else if (OGS_FSM_CHECK(&amf_ue->sm, gmm_state_registered)) {
                     /*
diff --git a/src/amf/nudm-build.c b/src/amf/nudm-build.c
index 37c897286..11adc3ad4 100644
--- a/src/amf/nudm-build.c
+++ b/src/amf/nudm-build.c
@@ -74,6 +74,48 @@ ogs_sbi_request_t *amf_nudm_uecm_build_registration(
     return request;
 }
 
+ogs_sbi_request_t *amf_nudm_uecm_build_registration_delete(
+        amf_ue_t *amf_ue, void *data)
+{
+    ogs_sbi_message_t message;
+    ogs_sbi_request_t *request = NULL;
+
+    OpenAPI_amf3_gpp_access_registration_modification_t
+        Amf3GppAccessRegistrationModification;
+
+    ogs_assert(amf_ue);
+    ogs_assert(amf_ue->supi);
+
+    memset(&message, 0, sizeof(message));
+    message.h.method = (char *)OGS_SBI_HTTP_METHOD_PATCH;
+    message.h.service.name = (char *)OGS_SBI_SERVICE_NAME_NUDM_UECM;
+    message.h.api.version = (char *)OGS_SBI_API_V1;
+    message.h.resource.component[0] = amf_ue->supi;
+    message.h.resource.component[1] =
+            (char *)OGS_SBI_RESOURCE_NAME_REGISTRATIONS;
+    message.h.resource.component[2] =
+            (char *)OGS_SBI_RESOURCE_NAME_AMF_3GPP_ACCESS;
+
+    memset(&Amf3GppAccessRegistrationModification, 0,
+            sizeof(Amf3GppAccessRegistrationModification));
+
+    Amf3GppAccessRegistrationModification.guami =
+            ogs_sbi_build_guami(amf_ue->guami);
+    Amf3GppAccessRegistrationModification.is_purge_flag = true;
+    Amf3GppAccessRegistrationModification.purge_flag = 1;
+
+    message.Amf3GppAccessRegistrationModification =
+            &Amf3GppAccessRegistrationModification;
+
+    request = ogs_sbi_build_request(&message);
+    ogs_assert(request);
+
+    if (Amf3GppAccessRegistrationModification.guami)
+        ogs_sbi_free_guami(Amf3GppAccessRegistrationModification.guami);
+
+    return request;
+}
+
 ogs_sbi_request_t *amf_nudm_sdm_build_get(amf_ue_t *amf_ue, void *data)
 {
     ogs_sbi_message_t message;
diff --git a/src/amf/nudm-build.h b/src/amf/nudm-build.h
index 8ccd7405e..a3c10968b 100644
--- a/src/amf/nudm-build.h
+++ b/src/amf/nudm-build.h
@@ -28,6 +28,8 @@ extern "C" {
 
 ogs_sbi_request_t *amf_nudm_uecm_build_registration(
         amf_ue_t *amf_ue, void *data);
+ogs_sbi_request_t *amf_nudm_uecm_build_registration_delete(
+        amf_ue_t *amf_ue, void *data);
 ogs_sbi_request_t *amf_nudm_sdm_build_get(amf_ue_t *amf_ue, void *data);
 
 #ifdef __cplusplus
diff --git a/src/udm/nudm-handler.c b/src/udm/nudm-handler.c
index 572fe3a03..2a0b8cb1e 100644
--- a/src/udm/nudm-handler.c
+++ b/src/udm/nudm-handler.c
@@ -336,6 +336,113 @@ bool udm_nudm_uecm_handle_registration(
     return true;
 }
 
+bool udm_nudm_uecm_handle_registration_update(
+    udm_ue_t *udm_ue, ogs_sbi_stream_t *stream, ogs_sbi_message_t *message)
+{
+    OpenAPI_amf3_gpp_access_registration_modification_t
+        *Amf3GppAccessRegistrationModification = NULL;
+    OpenAPI_guami_t *Guami = NULL;
+    ogs_guami_t recv_guami;
+    OpenAPI_list_t *PatchItemList = NULL;
+    OpenAPI_patch_item_t item;
+
+    ogs_assert(udm_ue);
+    ogs_assert(stream);
+    ogs_assert(message);
+
+    Amf3GppAccessRegistrationModification = message->Amf3GppAccessRegistrationModification;
+    if (!Amf3GppAccessRegistrationModification) {
+        ogs_error("[%s] No Amf3GppAccessRegistrationModification", udm_ue->supi);
+        ogs_assert(true ==
+            ogs_sbi_server_send_error(stream, OGS_SBI_HTTP_STATUS_BAD_REQUEST,
+                message, "No Amf3GppAccessRegistrationModification", udm_ue->supi));
+        return false;
+    }
+
+    Guami = Amf3GppAccessRegistrationModification->guami;
+    if (!Guami) {
+        ogs_error("[%s] No Guami", udm_ue->supi);
+        ogs_assert(true ==
+            ogs_sbi_server_send_error(stream, OGS_SBI_HTTP_STATUS_BAD_REQUEST,
+                message, "No Guami", udm_ue->supi));
+        return false;
+    }
+
+    if (!Guami->amf_id) {
+        ogs_error("[%s] No Guami.AmfId", udm_ue->supi);
+        ogs_assert(true ==
+            ogs_sbi_server_send_error(stream, OGS_SBI_HTTP_STATUS_BAD_REQUEST,
+                message, "No Guami.AmfId", udm_ue->supi));
+        return false;
+    }
+
+    if (!Guami->plmn_id) {
+        ogs_error("[%s] No PlmnId", udm_ue->supi);
+        ogs_assert(true ==
+            ogs_sbi_server_send_error(stream, OGS_SBI_HTTP_STATUS_BAD_REQUEST,
+                message, "No PlmnId", udm_ue->supi));
+        return false;
+    }
+
+    if (!Guami->plmn_id->mnc) {
+        ogs_error("[%s] No PlmnId.Mnc", udm_ue->supi);
+        ogs_assert(true ==
+            ogs_sbi_server_send_error(stream, OGS_SBI_HTTP_STATUS_BAD_REQUEST,
+                message, "No PlmnId.Mnc", udm_ue->supi));
+        return false;
+    }
+
+    if (!Guami->plmn_id->mcc) {
+        ogs_error("[%s] No PlmnId.Mcc", udm_ue->supi);
+        ogs_assert(true ==
+            ogs_sbi_server_send_error(stream, OGS_SBI_HTTP_STATUS_BAD_REQUEST,
+                message, "No PlmnId.Mcc", udm_ue->supi));
+        return false;
+    }
+
+    /* TS 29.503: 5.3.2.4.2 AMF deregistration for 3GPP access
+     * 2a. The UDM shall check whether the received GUAMI matches the stored
+     * GUAMI. If so, the UDM shall set the PurgeFlag. The UDM responds with
+     * "204 No Content".
+     * 2b. Otherwise the UDM responds with "403 Forbidden". */
+    ogs_sbi_parse_guami(&recv_guami, Guami);
+    if (memcmp(&recv_guami, &udm_ue->guami, sizeof(recv_guami)) != 0) {
+        ogs_error("[%s] Guami mismatch", udm_ue->supi);
+        ogs_assert(true ==
+            ogs_sbi_server_send_error(stream, OGS_SBI_HTTP_STATUS_FORBIDDEN,
+                message, "Guami mismatch", udm_ue->supi));
+    }
+
+
+    if (Amf3GppAccessRegistrationModification->is_purge_flag) {
+        udm_ue->amf_3gpp_access_registration->is_purge_flag =
+                Amf3GppAccessRegistrationModification->is_purge_flag;
+        udm_ue->amf_3gpp_access_registration->purge_flag =
+                Amf3GppAccessRegistrationModification->purge_flag;
+    }
+
+    PatchItemList = OpenAPI_list_create();
+    ogs_assert(PatchItemList);
+
+
+    if (Amf3GppAccessRegistrationModification->is_purge_flag) {
+        memset(&item, 0, sizeof(item));
+        item.op = OpenAPI_patch_operation_replace;
+        item.path = (char *)"PurgeFlag";
+        item.value = OpenAPI_any_type_create_bool(
+                Amf3GppAccessRegistrationModification->purge_flag);
+        ogs_assert(item.value);
+
+        OpenAPI_list_add(PatchItemList, &item);
+    }
+
+    ogs_assert(true ==
+        udm_sbi_discover_and_send(OpenAPI_nf_type_UDR, udm_ue, stream,
+            PatchItemList, udm_nudr_dr_build_patch_amf_context));
+
+    return true;
+}
+
 bool udm_nudm_sdm_handle_subscription_provisioned(
     udm_ue_t *udm_ue, ogs_sbi_stream_t *stream, ogs_sbi_message_t *recvmsg)
 {
diff --git a/src/udm/nudm-handler.h b/src/udm/nudm-handler.h
index c7a447e2e..c651f1b8e 100644
--- a/src/udm/nudm-handler.h
+++ b/src/udm/nudm-handler.h
@@ -33,6 +33,8 @@ bool udm_nudm_ueau_handle_result_confirmation_inform(
 
 bool udm_nudm_uecm_handle_registration(
     udm_ue_t *udm_ue, ogs_sbi_stream_t *stream, ogs_sbi_message_t *message);
+bool udm_nudm_uecm_handle_registration_update(
+    udm_ue_t *udm_ue, ogs_sbi_stream_t *stream, ogs_sbi_message_t *message);
 
 bool udm_nudm_sdm_handle_subscription_provisioned(
     udm_ue_t *udm_ue, ogs_sbi_stream_t *stream, ogs_sbi_message_t *recvmsg);
diff --git a/src/udm/nudr-build.c b/src/udm/nudr-build.c
index ee5b1ca9f..809aaa1c7 100644
--- a/src/udm/nudr-build.c
+++ b/src/udm/nudr-build.c
@@ -149,6 +149,50 @@ ogs_sbi_request_t *udm_nudr_dr_build_update_amf_context(
     return request;
 }
 
+ogs_sbi_request_t *udm_nudr_dr_build_patch_amf_context(
+        udm_ue_t *udm_ue, void *data)
+{
+    ogs_sbi_message_t message;
+    ogs_sbi_request_t *request = NULL;
+
+    OpenAPI_patch_item_t *pitem = NULL;
+    OpenAPI_lnode_t *node = NULL;
+
+    OpenAPI_list_t *PatchItemList = (OpenAPI_list_t *)data;
+
+    ogs_assert(udm_ue);
+    ogs_assert(PatchItemList);
+
+    memset(&message, 0, sizeof(message));
+    message.http.content_type = (char *)OGS_SBI_CONTENT_PATCH_TYPE;
+    message.h.method = (char *)OGS_SBI_HTTP_METHOD_PATCH;
+    message.h.service.name = (char *)OGS_SBI_SERVICE_NAME_NUDR_DR;
+    message.h.api.version = (char *)OGS_SBI_API_V1;
+    message.h.resource.component[0] =
+        (char *)OGS_SBI_RESOURCE_NAME_SUBSCRIPTION_DATA;
+    message.h.resource.component[1] = (char *)udm_ue->supi;
+    message.h.resource.component[2] =
+        (char *)OGS_SBI_RESOURCE_NAME_CONTEXT_DATA;
+    message.h.resource.component[3] =
+        (char *)OGS_SBI_RESOURCE_NAME_AMF_3GPP_ACCESS;
+
+    message.PatchItemList = PatchItemList;
+
+    request = ogs_sbi_build_request(&message);
+    ogs_assert(request);
+
+    if (PatchItemList) {
+        OpenAPI_list_for_each(PatchItemList, node) {
+            pitem = node->data;
+            if (pitem)
+                OpenAPI_any_type_free(pitem->value);
+        }
+        OpenAPI_list_free(PatchItemList);
+    }
+
+    return request;
+}
+
 ogs_sbi_request_t *udm_nudr_dr_build_query_subscription_provisioned(
         udm_ue_t *udm_ue, void *data)
 {
diff --git a/src/udm/nudr-build.h b/src/udm/nudr-build.h
index 7859c826b..a3b73f376 100644
--- a/src/udm/nudr-build.h
+++ b/src/udm/nudr-build.h
@@ -34,6 +34,8 @@ ogs_sbi_request_t *udm_nudr_dr_build_update_authentication_status(
         udm_ue_t *udm_ue, void *data);
 ogs_sbi_request_t *udm_nudr_dr_build_update_amf_context(
         udm_ue_t *udm_ue, void *data);
+ogs_sbi_request_t *udm_nudr_dr_build_patch_amf_context(
+        udm_ue_t *udm_ue, void *data);
 
 #ifdef __cplusplus
 }
diff --git a/src/udm/nudr-handler.c b/src/udm/nudr-handler.c
index a7c9ea57b..14ec9008c 100644
--- a/src/udm/nudr-handler.c
+++ b/src/udm/nudr-handler.c
@@ -406,6 +406,34 @@ bool udm_nudr_dr_handle_subscription_context(
         return false;
     }
 
+    SWITCH(recvmsg->h.method)
+    CASE(OGS_SBI_HTTP_METHOD_PATCH)
+        SWITCH(recvmsg->h.resource.component[3])
+        CASE(OGS_SBI_RESOURCE_NAME_AMF_3GPP_ACCESS)
+            memset(&sendmsg, 0, sizeof(sendmsg));
+
+            response = ogs_sbi_build_response(
+                    &sendmsg, OGS_SBI_HTTP_STATUS_NO_CONTENT);
+            ogs_assert(response);
+            ogs_assert(true == ogs_sbi_server_send_response(stream, response));
+            return true;
+
+        DEFAULT
+            strerror = ogs_msprintf("[%s] Invalid resource name [%s]",
+                    udm_ue->supi, recvmsg->h.resource.component[3]);
+            ogs_assert(strerror);
+
+            ogs_error("%s", strerror);
+            ogs_assert(true ==
+                ogs_sbi_server_send_error(
+                    stream, OGS_SBI_HTTP_STATUS_BAD_REQUEST,
+                    recvmsg, strerror, NULL));
+            ogs_free(strerror);
+            return false;
+        END
+    END
+
+
     SWITCH(recvmsg->h.resource.component[3])
     CASE(OGS_SBI_RESOURCE_NAME_AMF_3GPP_ACCESS)
         Amf3GppAccessRegistration = udm_ue->amf_3gpp_access_registration;
diff --git a/src/udm/ue-sm.c b/src/udm/ue-sm.c
index 7439875b0..3fcf2fe08 100644
--- a/src/udm/ue-sm.c
+++ b/src/udm/ue-sm.c
@@ -101,6 +101,21 @@ void udm_ue_state_operational(ogs_fsm_t *s, udm_event_t *e)
                     udm_nudm_uecm_handle_registration(udm_ue, stream, message);
                     break;
 
+                DEFAULT
+                    ogs_error("[%s] Invalid resource name [%s]",
+                            udm_ue->suci, message->h.resource.component[1]);
+                    ogs_assert(true ==
+                        ogs_sbi_server_send_error(stream,
+                            OGS_SBI_HTTP_STATUS_BAD_REQUEST, message,
+                            "Invalid HTTP method", message->h.method));
+                END
+                break;
+            CASE(OGS_SBI_HTTP_METHOD_PATCH)
+                SWITCH(message->h.resource.component[1])
+                CASE(OGS_SBI_RESOURCE_NAME_REGISTRATIONS)
+                    udm_nudm_uecm_handle_registration_update(udm_ue, stream, message);
+                    break;
+
                 DEFAULT
                     ogs_error("[%s] Invalid resource name [%s]",
                             udm_ue->suci, message->h.resource.component[1]);
diff --git a/src/udr/nudr-handler.c b/src/udr/nudr-handler.c
index 684e51689..09a73d8de 100644
--- a/src/udr/nudr-handler.c
+++ b/src/udr/nudr-handler.c
@@ -303,6 +303,30 @@ bool udr_nudr_dr_handle_subscription_context(
 
             return true;
 
+        CASE(OGS_SBI_HTTP_METHOD_PATCH)
+            OpenAPI_list_t *PatchItemList;
+
+            PatchItemList = recvmsg->PatchItemList;
+            if (!PatchItemList) {
+                ogs_error("[%s] No PatchItemList", supi);
+                ogs_assert(true ==
+                    ogs_sbi_server_send_error(
+                        stream, OGS_SBI_HTTP_STATUS_BAD_REQUEST,
+                        recvmsg, "No PatchItemList", supi));
+                return false;
+            }
+
+            /* TODO: parse PatchItemList */
+
+            memset(&sendmsg, 0, sizeof(sendmsg));
+
+            response = ogs_sbi_build_response(
+                    &sendmsg, OGS_SBI_HTTP_STATUS_NO_CONTENT);
+            ogs_assert(response);
+            ogs_assert(true == ogs_sbi_server_send_response(stream, response));
+
+            return true;
+
         DEFAULT
             ogs_error("Invalid HTTP method [%s]", recvmsg->h.method);
             ogs_assert(true ==