diff --git a/src/sgwc/pfcp-path.c b/src/sgwc/pfcp-path.c
index 7e67db6670..aa2e870664 100644
--- a/src/sgwc/pfcp-path.c
+++ b/src/sgwc/pfcp-path.c
@@ -160,25 +160,71 @@ void sgwc_pfcp_close(void)
     ogs_socknode_remove_all(&ogs_pfcp_self()->pfcp_list6);
 }
 
-static void sess_timeout(ogs_pfcp_xact_t *xact, void *data)
+static void sess_timeout(ogs_pfcp_xact_t *pfcp_xact, void *data)
 {
-    uint8_t type;
+    uint8_t pfcp_type;
 
-    ogs_assert(xact);
-    type = xact->seq[0].type;
+    uint8_t gtp_cause;
+    uint8_t gtp_type;
+    ogs_gtp_xact_t * s11_xact = NULL;
+    sgwc_sess_t *sess = data;
+    sgwc_ue_t *sgwc_ue = NULL;
 
-    switch (type) {
+    ogs_assert(pfcp_xact);
+    ogs_assert(sess);
+
+    s11_xact = pfcp_xact->assoc_xact;
+    ogs_assert(s11_xact);
+
+    switch (s11_xact->gtp_version) {
+    case 1:
+        gtp_cause = OGS_GTP1_CAUSE_NETWORK_FAILURE;
+        break;
+    case 2:
+        gtp_cause = OGS_GTP2_CAUSE_REMOTE_PEER_NOT_RESPONDING;
+        break;
+    }
+
+    sgwc_ue = sess->sgwc_ue;
+
+    pfcp_type = pfcp_xact->seq[0].type;
+    switch (pfcp_type) {
     case OGS_PFCP_SESSION_ESTABLISHMENT_REQUEST_TYPE:
-        ogs_error("No PFCP session establishment response");
+        ogs_error("Timeout: No PFCP session establishment response");
+        ogs_gtp_send_error_message(
+                s11_xact, sgwc_ue ? sgwc_ue->mme_s11_teid : 0,
+                OGS_GTP2_CREATE_SESSION_RESPONSE_TYPE, gtp_cause);
         break;
     case OGS_PFCP_SESSION_MODIFICATION_REQUEST_TYPE:
-        ogs_error("No PFCP session modification response");
+        ogs_error("Timeout: No PFCP session modification response");
+
+        // multiple gtp message-types are translated to pfcp session mod request
+        switch (s11_xact->seq[0].type) {
+        case OGS_GTP2_MODIFY_BEARER_REQUEST_TYPE:
+            gtp_type = OGS_GTP2_MODIFY_BEARER_RESPONSE_TYPE;
+            break;
+        case OGS_GTP2_RELEASE_ACCESS_BEARERS_REQUEST_TYPE:
+            gtp_type = OGS_GTP2_RELEASE_ACCESS_BEARERS_RESPONSE_TYPE;
+            break;
+        default:
+            ogs_error("GTP request type not implemented: %d", s11_xact->seq[0].type);
+            gtp_type = OGS_GTP2_MODIFY_BEARER_RESPONSE_TYPE;
+            break;
+        }
+
+        ogs_gtp_send_error_message(
+                s11_xact, sgwc_ue ? sgwc_ue->mme_s11_teid : 0,
+                gtp_type, gtp_cause);
         break;
     case OGS_PFCP_SESSION_DELETION_REQUEST_TYPE:
-        ogs_error("No PFCP session deletion response");
+        ogs_error("Timeout: No PFCP session deletion response");
+        ogs_gtp_send_error_message(
+                s11_xact, sgwc_ue ? sgwc_ue->mme_s11_teid : 0,
+                OGS_GTP2_DELETE_SESSION_RESPONSE_TYPE, gtp_cause);
+        sgwc_sess_remove(sess);
         break;
     default:
-        ogs_error("Not implemented [type:%d]", type);
+        ogs_error("PFCP request type not implemented [type:%d]", pfcp_type);
         break;
     }
 }
diff --git a/src/smf/context.h b/src/smf/context.h
index 51f4f43d19..672d30a384 100644
--- a/src/smf/context.h
+++ b/src/smf/context.h
@@ -412,6 +412,8 @@ typedef struct smf_sess_s {
     ogs_gtp_node_t  *gnode;
     ogs_pfcp_node_t *pfcp_node;
     bool pfcp_established;
+
+    ogs_pfcp_xact_t *timeout_xact;
     
     ogs_timer_t *timer_gx_cca;
     ogs_timer_t *timer_gy_cca;
diff --git a/src/smf/event.h b/src/smf/event.h
index 64effdbe67..8ca4ae6f31 100644
--- a/src/smf/event.h
+++ b/src/smf/event.h
@@ -52,7 +52,8 @@ typedef enum {
     SMF_EVT_GX_MESSAGE,
     SMF_EVT_GY_MESSAGE,
     SMF_EVT_DIAMETER_TIMER,
-
+    SMF_EVT_PFCP_TIMEOUT,
+    
     SMF_EVT_N4_MESSAGE,
     SMF_EVT_N4_TIMER,
     SMF_EVT_N4_NO_HEARTBEAT,
diff --git a/src/smf/gsm-sm.c b/src/smf/gsm-sm.c
index 15a8caa042..43fa97c63e 100644
--- a/src/smf/gsm-sm.c
+++ b/src/smf/gsm-sm.c
@@ -691,6 +691,8 @@ void smf_gsm_state_wait_pfcp_establishment(ogs_fsm_t *s, smf_event_t *e)
     ogs_pfcp_message_t *pfcp_message = NULL;
     int rv;
 
+    ogs_gtp_xact_t *gtp_xact = NULL;
+
     ogs_assert(s);
     ogs_assert(e);
 
@@ -779,6 +781,29 @@ void smf_gsm_state_wait_pfcp_establishment(ogs_fsm_t *s, smf_event_t *e)
             ogs_error("cannot handle PFCP message type[%d]",
                     pfcp_message->h.type);
         }
+        break;
+
+    case SMF_EVT_PFCP_TIMEOUT:
+        switch(e->h.timer_id) {
+        case SMF_TIMEOUT_PFCP_SER:
+            ogs_error("PFCP timeout waiting for Session Establishment Response");
+
+            gtp_xact = (ogs_gtp_xact_t *) sess->timeout_xact->assoc_xact;            
+
+            switch (gtp_xact->gtp_version) {
+                case 1:
+                    gtp_cause = OGS_GTP1_CAUSE_NETWORK_FAILURE;
+                    break;
+                case 2:
+                    gtp_cause = OGS_GTP2_CAUSE_REMOTE_PEER_NOT_RESPONDING;
+                    break;
+            }
+            send_gtp_create_err_msg(sess, gtp_xact, gtp_cause);
+            break;
+
+        default:
+            ogs_error("Unknown SMF_EVT_PFCP_TIMEOUT timer id [%d]", e->h.timer_id);
+        }
     }
 }
 
@@ -1369,6 +1394,30 @@ void smf_gsm_state_wait_pfcp_deletion(ogs_fsm_t *s, smf_event_t *e)
             ogs_error("cannot handle PFCP message type[%d]",
                     pfcp_message->h.type);
         }
+        break;
+
+    case SMF_EVT_PFCP_TIMEOUT:
+        switch(e->h.timer_id) {
+        case SMF_TIMEOUT_PFCP_SDR:
+            ogs_error("PFCP timeout waiting for Session Deletion Response");
+
+            gtp_xact = (ogs_gtp_xact_t *) sess->timeout_xact->assoc_xact;
+
+            switch (gtp_xact->gtp_version) {
+                case 1:
+                    gtp_cause = OGS_GTP1_CAUSE_NETWORK_FAILURE;
+                    break;
+                case 2:
+                    gtp_cause = OGS_GTP2_CAUSE_REMOTE_PEER_NOT_RESPONDING;
+                    break;
+            }
+            send_gtp_delete_err_msg(sess, gtp_xact, gtp_cause);
+            break;
+
+        default:
+            ogs_error("Unknown SMF_EVT_PFCP_TIMEOUT timer id [%d]", e->h.timer_id);
+        }
+        break;
     }
 }
 
diff --git a/src/smf/pfcp-path.c b/src/smf/pfcp-path.c
index ac9b3dd6c9..cebfb5b234 100644
--- a/src/smf/pfcp-path.c
+++ b/src/smf/pfcp-path.c
@@ -277,19 +277,23 @@ static void sess_5gc_timeout(ogs_pfcp_xact_t *xact, void *data)
 static void sess_epc_timeout(ogs_pfcp_xact_t *xact, void *data)
 {
     uint8_t type;
+    smf_sess_t *sess;
 
     ogs_assert(xact);
     type = xact->seq[0].type;
 
+    sess = data;
+    sess->timeout_xact = xact;
+
     switch (type) {
     case OGS_PFCP_SESSION_ESTABLISHMENT_REQUEST_TYPE:
-        ogs_warn("No PFCP session establishment response");
+        smf_timeout_pfcp_no_ser(data);
         break;
     case OGS_PFCP_SESSION_MODIFICATION_REQUEST_TYPE:
-        ogs_error("No PFCP session modification response");
+        smf_timeout_pfcp_no_smr(data);
         break;
     case OGS_PFCP_SESSION_DELETION_REQUEST_TYPE:
-        ogs_error("No PFCP session deletion response");
+        smf_timeout_pfcp_no_sdr(data);
         break;
     default:
         ogs_error("Not implemented [type:%d]", type);
@@ -306,7 +310,7 @@ static void bearer_epc_timeout(ogs_pfcp_xact_t *xact, void *data)
 
     switch (type) {
     case OGS_PFCP_SESSION_MODIFICATION_REQUEST_TYPE:
-        ogs_error("No PFCP session modification response");
+        smf_timeout_pfcp_no_smr(data);
         break;
     default:
         ogs_error("Not implemented [type:%d]", type);
diff --git a/src/smf/smf-sm.c b/src/smf/smf-sm.c
index c6befa43ab..67ca2f2303 100644
--- a/src/smf/smf-sm.c
+++ b/src/smf/smf-sm.c
@@ -366,6 +366,15 @@ void smf_state_operational(ogs_fsm_t *s, smf_event_t *e)
         }
         break;
 
+    case SMF_EVT_PFCP_TIMEOUT:
+        ogs_assert(e);
+        sess = e->sess;
+        if (sess) {
+            ogs_assert(OGS_FSM_STATE(&sess->sm));
+            ogs_fsm_dispatch(&sess->sm, e);            
+            }
+        break;
+
     case SMF_EVT_S6B_MESSAGE:
         ogs_assert(e);
         s6b_message = e->s6b_message;
diff --git a/src/smf/timer.c b/src/smf/timer.c
index 31a6b94956..ece92836bb 100644
--- a/src/smf/timer.c
+++ b/src/smf/timer.c
@@ -72,6 +72,14 @@ static void timer_send_event(int timer_id, void *data)
         e->gx_message = old_e->gx_message;
         e->gtp_xact = old_e->gtp_xact;
         break;
+    case SMF_TIMEOUT_PFCP_SER:
+    case SMF_TIMEOUT_PFCP_SDR:
+    case SMF_TIMEOUT_PFCP_SMR:
+        e = smf_event_new(SMF_EVT_PFCP_TIMEOUT);
+        ogs_assert(e);
+        e->h.timer_id = timer_id;
+        e->sess = data;
+        break;
     default:
         ogs_fatal("Unknown timer id[%d]", timer_id);
         ogs_assert_if_reached();
@@ -105,3 +113,18 @@ void smf_timer_gy_no_cca(void *data)
 {
     timer_send_event(SMF_TIMER_GY_CCA, data);
 }
+
+void smf_timeout_pfcp_no_ser(void *data)
+{
+    timer_send_event(SMF_TIMEOUT_PFCP_SER, data);
+}
+
+void smf_timeout_pfcp_no_sdr(void *data)
+{
+    timer_send_event(SMF_TIMEOUT_PFCP_SDR, data);
+}
+
+void smf_timeout_pfcp_no_smr(void *data)
+{
+    timer_send_event(SMF_TIMEOUT_PFCP_SMR, data);
+}
diff --git a/src/smf/timer.h b/src/smf/timer.h
index b35702e1cb..89f5a30508 100644
--- a/src/smf/timer.h
+++ b/src/smf/timer.h
@@ -34,6 +34,9 @@ typedef enum {
     SMF_TIMER_PFCP_NO_HEARTBEAT,
     SMF_TIMER_GX_CCA,
     SMF_TIMER_GY_CCA,
+    SMF_TIMEOUT_PFCP_SER,
+    SMF_TIMEOUT_PFCP_SDR,
+    SMF_TIMEOUT_PFCP_SMR,
 
     MAX_NUM_OF_SMF_TIMER,
 
@@ -46,6 +49,10 @@ void smf_timer_pfcp_no_heartbeat(void *data);
 void smf_timer_gx_no_cca(void *data);
 void smf_timer_gy_no_cca(void *data);
 
+void smf_timeout_pfcp_no_ser(void *data);
+void smf_timeout_pfcp_no_sdr(void *data);
+void smf_timeout_pfcp_no_smr(void *data);
+
 #ifdef __cplusplus
 }
 #endif