diff --git a/TESTS/netsocket/udp/udpsocket_echotest_burst.cpp b/TESTS/netsocket/udp/udpsocket_echotest_burst.cpp
index 9e5c6c9bfc..87742c64db 100644
--- a/TESTS/netsocket/udp/udpsocket_echotest_burst.cpp
+++ b/TESTS/netsocket/udp/udpsocket_echotest_burst.cpp
@@ -100,7 +100,9 @@ void UDPSOCKET_ECHOTEST_BURST()
             if (check_oversized_packets(sent, tx_buffers[x].len)) {
                 TEST_IGNORE_MESSAGE("This device does not handle oversized packets");
             }
-            TEST_ASSERT_EQUAL(tx_buffers[x].len, sent);
+            if (sent != NSAPI_ERROR_NO_MEMORY) {
+                TEST_ASSERT_EQUAL(tx_buffers[x].len, sent);
+            }
         }
 
         bt_total = 0;
diff --git a/features/cellular/framework/AT/AT_CellularStack.cpp b/features/cellular/framework/AT/AT_CellularStack.cpp
index bfa502f86d..0606da4851 100644
--- a/features/cellular/framework/AT/AT_CellularStack.cpp
+++ b/features/cellular/framework/AT/AT_CellularStack.cpp
@@ -233,8 +233,10 @@ nsapi_error_t AT_CellularStack::socket_close(nsapi_socket_t handle)
         tr_info("Socket %d close (id %d, started %d, error %d)", index, sock_id, socket->started, err);
     }
 
+    _socket_mutex.lock();
     _socket[index] = NULL;
     delete socket;
+    _socket_mutex.unlock();
 
     _at.unlock();
 
diff --git a/features/cellular/framework/AT/AT_CellularStack.h b/features/cellular/framework/AT/AT_CellularStack.h
index 8aef39a143..db966ee272 100644
--- a/features/cellular/framework/AT/AT_CellularStack.h
+++ b/features/cellular/framework/AT/AT_CellularStack.h
@@ -114,7 +114,8 @@ protected:
             started(false),
             tx_ready(false),
             tls_socket(false),
-            pending_bytes(0)
+            pending_bytes(0),
+            txfull_event(false)
         {
         }
         // Socket identifier, generally it will be the socket ID assigned by the
@@ -132,6 +133,7 @@ protected:
         bool tx_ready; // socket is ready for sending on modem stack
         bool tls_socket; // socket uses modem's internal TLS socket functionality
         nsapi_size_t pending_bytes; // The number of received bytes pending
+        bool txfull_event; // socket event after wouldblock
     };
 
     /**
@@ -231,10 +233,10 @@ private:
 
     int get_socket_index_by_port(uint16_t port);
 
-    // mutex for write/read to a _socket array, needed when multiple threads may open sockets simultaneously
+protected:
+    // mutex for write/read to a _socket array, needed when multiple threads may use sockets simultaneously
     PlatformMutex _socket_mutex;
 
-protected:
     ATHandler &_at;
 
     AT_CellularDevice &_device;
diff --git a/features/cellular/framework/targets/QUECTEL/BC95/QUECTEL_BC95_CellularStack.cpp b/features/cellular/framework/targets/QUECTEL/BC95/QUECTEL_BC95_CellularStack.cpp
index badf70c3a5..2f4e3550a4 100644
--- a/features/cellular/framework/targets/QUECTEL/BC95/QUECTEL_BC95_CellularStack.cpp
+++ b/features/cellular/framework/targets/QUECTEL/BC95/QUECTEL_BC95_CellularStack.cpp
@@ -15,17 +15,28 @@
  * limitations under the License.
  */
 
+#include "rtos/ThisThread.h"
+#include "mbed_error.h"
+#include "platform/mbed_atomic.h"
+#include "events/EventQueue.h"
+#include "events/mbed_shared_queues.h"
+
 #include "QUECTEL_BC95_CellularStack.h"
 #include "CellularUtil.h"
 #include "CellularLog.h"
 
 #define PACKET_SIZE_MAX 1358
+#define TXFULL_EVENT_TIMEOUT (1 * 1000) // ms
+
+#define AT_UPLINK_BUSY          159
+#define AT_UART_BUFFER_ERROR    536
+#define AT_BACK_OFF_TIMER       537
 
 using namespace mbed;
 using namespace mbed_cellular_util;
 
 QUECTEL_BC95_CellularStack::QUECTEL_BC95_CellularStack(ATHandler &atHandler, int cid, nsapi_ip_stack_t stack_type, AT_CellularDevice &device) :
-    AT_CellularStack(atHandler, cid, stack_type, device)
+    AT_CellularStack(atHandler, cid, stack_type, device), _event_queue(mbed_event_queue()), _txfull_event_id(0)
 {
     _at.set_urc_handler("+NSONMI:", mbed::Callback<void()>(this, &QUECTEL_BC95_CellularStack::urc_nsonmi));
     _at.set_urc_handler("+NSOCLI:", mbed::Callback<void()>(this, &QUECTEL_BC95_CellularStack::urc_nsocli));
@@ -33,6 +44,10 @@ QUECTEL_BC95_CellularStack::QUECTEL_BC95_CellularStack(ATHandler &atHandler, int
 
 QUECTEL_BC95_CellularStack::~QUECTEL_BC95_CellularStack()
 {
+    if (_txfull_event_id) {
+        _event_queue->cancel(_txfull_event_id);
+    }
+
     _at.set_urc_handler("+NSONMI:", NULL);
     _at.set_urc_handler("+NSOCLI:", NULL);
 }
@@ -130,6 +145,9 @@ nsapi_error_t QUECTEL_BC95_CellularStack::socket_close_impl(int sock_id)
     if (sock && sock->closed) {
         return NSAPI_ERROR_OK;
     }
+
+    sock->txfull_event = false;
+
     nsapi_error_t err = _at.at_cmd_discard("+NSOCL", "=", "%d", sock_id);
 
     tr_info("Close socket: %d error: %d", sock_id, err);
@@ -186,6 +204,8 @@ nsapi_size_or_error_t QUECTEL_BC95_CellularStack::socket_sendto_impl(CellularSoc
         return NSAPI_ERROR_PARAMETER;
     }
 
+    int retry = 0;
+retry_send:
     if (socket->proto == NSAPI_UDP) {
         _at.cmd_start("AT+NSOST=");
         _at.write_int(socket->id);
@@ -212,6 +232,36 @@ nsapi_size_or_error_t QUECTEL_BC95_CellularStack::socket_sendto_impl(CellularSoc
         return sent_len;
     }
 
+    // check for network congestion
+    device_err_t err = _at.get_last_device_error();
+    if (err.errType == DeviceErrorTypeErrorCME &&
+            (err.errCode == AT_UART_BUFFER_ERROR || err.errCode == AT_BACK_OFF_TIMER) || err.errCode == AT_UPLINK_BUSY) {
+        if (socket->proto == NSAPI_UDP) {
+            if (retry < 3) {
+                retry++;
+                tr_warn("Socket %d sendto EAGAIN", socket->id);
+                rtos::ThisThread::sleep_for(30);
+                _at.clear_error();
+                goto retry_send;
+            }
+            return NSAPI_ERROR_NO_MEMORY;
+        }
+        _socket_mutex.lock();
+        if (!socket->txfull_event && !_txfull_event_id) {
+            tr_warn("socket %d tx full", socket->id);
+            socket->txfull_event = true;
+            _txfull_event_id = _event_queue->call_in(TXFULL_EVENT_TIMEOUT, callback(this, &QUECTEL_BC95_CellularStack::txfull_event_timeout));
+            if (!_txfull_event_id) {
+                MBED_ERROR(MBED_MAKE_ERROR(MBED_MODULE_DRIVER, MBED_ERROR_CODE_ENOMEM), \
+                           "QUECTEL_BC95_CellularStack::socket_sendto_impl(): unable to add event to queue. Increase \"events.shared-eventsize\"\n");
+                _socket_mutex.unlock();
+                return NSAPI_ERROR_NO_MEMORY;
+            }
+        }
+        _socket_mutex.unlock();
+        return NSAPI_ERROR_WOULD_BLOCK;
+    }
+
     return _at.get_last_error();
 }
 
@@ -234,7 +284,7 @@ nsapi_size_or_error_t QUECTEL_BC95_CellularStack::socket_recvfrom_impl(CellularS
     _at.read_string(ip_address, sizeof(ip_address));
     port = _at.read_int();
     recv_len = _at.read_int();
-    int hexlen = _at.read_hex_string((char *)buffer, size);
+    int hexlen = _at.read_hex_string((char *)buffer, recv_len);
     // remaining length
     _at.skip_param();
     _at.resp_stop();
@@ -253,3 +303,17 @@ nsapi_size_or_error_t QUECTEL_BC95_CellularStack::socket_recvfrom_impl(CellularS
     }
     return recv_len;
 }
+
+void QUECTEL_BC95_CellularStack::txfull_event_timeout()
+{
+    _socket_mutex.lock();
+    _txfull_event_id = 0;
+    for (int i = 0; i < get_max_socket_count(); i++) {
+        CellularSocket *sock = _socket[i];
+        if (sock && sock->_cb && sock->txfull_event) {
+            sock->txfull_event = false;
+            sock->_cb(sock->_data);
+        }
+    }
+    _socket_mutex.unlock();
+}
diff --git a/features/cellular/framework/targets/QUECTEL/BC95/QUECTEL_BC95_CellularStack.h b/features/cellular/framework/targets/QUECTEL/BC95/QUECTEL_BC95_CellularStack.h
index 46546edf0f..8229cbfb6e 100644
--- a/features/cellular/framework/targets/QUECTEL/BC95/QUECTEL_BC95_CellularStack.h
+++ b/features/cellular/framework/targets/QUECTEL/BC95/QUECTEL_BC95_CellularStack.h
@@ -58,6 +58,10 @@ private:
     // URC handlers
     void urc_nsonmi();
     void urc_nsocli();
+
+    events::EventQueue *_event_queue;
+    int _txfull_event_id;
+    void txfull_event_timeout();
 };
 } // namespace mbed
 #endif /* QUECTEL_BC95_CELLULARSTACK_H_ */