diff --git a/src/mme/emm-sm.c b/src/mme/emm-sm.c
index 730afbcdd..c3a1a5d5c 100644
--- a/src/mme/emm-sm.c
+++ b/src/mme/emm-sm.c
@@ -60,11 +60,25 @@ static void common_register_state(ogs_fsm_t *s, mme_event_t *e);
 
 void emm_state_de_registered(ogs_fsm_t *s, mme_event_t *e)
 {
+    mme_ue_t *mme_ue = NULL;
     ogs_assert(s);
     ogs_assert(e);
 
     mme_sm_debug(e);
 
+    mme_ue = e->mme_ue;
+    ogs_assert(mme_ue);
+
+    switch (e->id) {
+    case OGS_FSM_ENTRY_SIG:
+        CLEAR_MME_UE_ALL_TIMERS(mme_ue);
+        break;
+    case OGS_FSM_EXIT_SIG:
+        break;
+    default:
+        break;
+    }
+
     common_register_state(s, e);
 }
 
@@ -633,7 +647,7 @@ void emm_state_authentication(ogs_fsm_t *s, mme_event_t *e)
                     mme_timer_get_name(e->timer_id), e->timer_id);
             break;
         }
-        return;
+        break;
     default:
         ogs_error("Unknown event[%s]", mme_event_get_name(e));
         break;
@@ -776,7 +790,7 @@ void emm_state_security_mode(ogs_fsm_t *s, mme_event_t *e)
                     mme_timer_get_name(e->timer_id), e->timer_id);
             break;
         }
-        return;
+        break;
     default:
         ogs_error("Unknown event[%s]", mme_event_get_name(e));
         break;
@@ -810,6 +824,9 @@ void emm_state_initial_context_setup(ogs_fsm_t *s, mme_event_t *e)
         case NAS_ATTACH_COMPLETE:
             ogs_debug("[EMM] Attach complete");
             ogs_debug("    IMSI[%s]", mme_ue->imsi_bcd);
+
+            CLEAR_MME_UE_TIMER(mme_ue->t3450);
+
             rv = emm_handle_attach_complete(
                     mme_ue, &message->emm.attach_complete);
             if (rv != OGS_OK) {
@@ -865,6 +882,27 @@ void emm_state_initial_context_setup(ogs_fsm_t *s, mme_event_t *e)
             break;
         }
         break;
+    case MME_EVT_EMM_TIMER:
+        switch (e->timer_id) {
+        case MME_TIMER_T3450:
+            if (mme_ue->t3450.retry_count >=
+                    mme_timer_cfg(MME_TIMER_T3450)->max_count) {
+                ogs_warn("[EMM] Retransmission of IMSI[%s] failed. "
+                        "Stop retransmission",
+                        mme_ue->imsi_bcd);
+                CLEAR_MME_UE_TIMER(mme_ue->t3450);
+                OGS_FSM_TRAN(&mme_ue->sm, &emm_state_exception);
+            } else {
+                mme_ue->t3450.retry_count++;
+                nas_send_attach_accept(mme_ue);
+            }
+            break;
+        default:
+            ogs_error("Unknown timer[%s:%d]",
+                    mme_timer_get_name(e->timer_id), e->timer_id);
+            break;
+        }
+        break;
     default:
         ogs_error("Unknown event[%s]", mme_event_get_name(e));
         break;
diff --git a/src/mme/esm-handler.c b/src/mme/esm-handler.c
index 585ed6e26..542f9e805 100644
--- a/src/mme/esm-handler.c
+++ b/src/mme/esm-handler.c
@@ -140,10 +140,12 @@ int esm_handle_information_response(mme_sess_t *sess,
             mme_vlr_t *vlr = mme_vlr_find_by_tai(&mme_ue->tai);
             mme_ue->vlr = vlr;
 
-            if (vlr)
+            if (vlr) {
                 sgsap_send_location_update_request(mme_ue);
-            else
+            } else {
+                CLEAR_MME_UE_TIMER(mme_ue->t3450);
                 nas_send_attach_accept(mme_ue);
+            }
         } else {
             rv = mme_gtp_send_create_session_request(sess);
             ogs_assert(rv == OGS_OK);
diff --git a/src/mme/mme-s11-handler.c b/src/mme/mme-s11-handler.c
index f79717014..4193efd10 100644
--- a/src/mme/mme-s11-handler.c
+++ b/src/mme/mme-s11-handler.c
@@ -113,10 +113,12 @@ void mme_s11_handle_create_session_response(
         mme_vlr_t *vlr = mme_vlr_find_by_tai(&mme_ue->tai);
         mme_ue->vlr = vlr;
 
-        if (vlr)
+        if (vlr) {
             sgsap_send_location_update_request(mme_ue);
-        else
+        } else {
+            CLEAR_MME_UE_TIMER(mme_ue->t3450);
             nas_send_attach_accept(mme_ue);
+        }
 
     } else if (OGS_FSM_CHECK(&mme_ue->sm, emm_state_registered)) {
         nas_send_activate_default_bearer_context_request(bearer);
diff --git a/src/mme/nas-path.c b/src/mme/nas-path.c
index 1fefa435c..cf0b37b63 100644
--- a/src/mme/nas-path.c
+++ b/src/mme/nas-path.c
@@ -98,14 +98,23 @@ int nas_send_attach_accept(mme_ue_t *mme_ue)
     ogs_assert(bearer);
     ogs_assert(mme_bearer_next(bearer) == NULL);
 
-    rv = esm_build_activate_default_bearer_context_request(&esmbuf, sess);
-    ogs_assert(rv == OGS_OK && esmbuf);
+    if (mme_ue->t3450.pkbuf) {
+        s1apbuf = mme_ue->t3450.pkbuf;
 
-    rv = emm_build_attach_accept(&emmbuf, mme_ue, esmbuf);
-    ogs_assert(rv == OGS_OK && emmbuf);
+    } else {
+        rv = esm_build_activate_default_bearer_context_request(&esmbuf, sess);
+        ogs_assert(rv == OGS_OK && esmbuf);
 
-    rv = s1ap_build_initial_context_setup_request(&s1apbuf, mme_ue, emmbuf);
-    ogs_assert(rv == OGS_OK && s1apbuf);
+        rv = emm_build_attach_accept(&emmbuf, mme_ue, esmbuf);
+        ogs_assert(rv == OGS_OK && emmbuf);
+
+        rv = s1ap_build_initial_context_setup_request(&s1apbuf, mme_ue, emmbuf);
+        ogs_assert(rv == OGS_OK && s1apbuf);
+    }
+
+    mme_ue->t3450.pkbuf = ogs_pkbuf_copy(s1apbuf);
+    ogs_timer_start(mme_ue->t3450.timer, 
+            mme_timer_cfg(MME_TIMER_T3450)->duration);
 
     rv = nas_send_to_enb(mme_ue, s1apbuf);
     ogs_assert(rv == OGS_OK);
diff --git a/src/mme/sgsap-handler.c b/src/mme/sgsap-handler.c
index 4023a9eed..1c510e5b7 100644
--- a/src/mme/sgsap-handler.c
+++ b/src/mme/sgsap-handler.c
@@ -102,6 +102,7 @@ void sgsap_handle_location_update_accept(mme_vlr_t *vlr, ogs_pkbuf_t *pkbuf)
         ogs_debug("    P-TMSI[0x%08x]", mme_ue->p_tmsi);
     }
 
+    CLEAR_MME_UE_TIMER(mme_ue->t3450);
     nas_send_attach_accept(mme_ue);
 
     return;