diff --git a/features/cellular/framework/targets/UBLOX/AT/UBLOX_AT.cpp b/features/cellular/framework/targets/UBLOX/AT/UBLOX_AT.cpp
index 62e44d3eec..bc42248b27 100644
--- a/features/cellular/framework/targets/UBLOX/AT/UBLOX_AT.cpp
+++ b/features/cellular/framework/targets/UBLOX/AT/UBLOX_AT.cpp
@@ -94,26 +94,28 @@ nsapi_error_t UBLOX_AT::init()
     _at->flush();
     _at->at_cmd_discard("", "");
 
-#ifdef TARGET_UBLOX_C027
-    _at->at_cmd_discard("+CFUN", "=0");
+    nsapi_error_t err = NSAPI_ERROR_OK;
 
-    if (_at->get_last_error() == NSAPI_ERROR_OK) {
+#ifdef TARGET_UBLOX_C027
+    err = _at->at_cmd_discard("+CFUN", "=0");
+
+    if (err == NSAPI_ERROR_OK) {
         _at->at_cmd_discard("E0", ""); // echo off
         _at->at_cmd_discard("+CMEE", "=1"); // verbose responses
         config_authentication_parameters();
-        _at->at_cmd_discard("+CFUN", "=1"); // set full functionality
+        err = _at->at_cmd_discard("+CFUN", "=1"); // set full functionality
     }
 #else
-    _at->at_cmd_discard("+CFUN", "=4");
-    if (_at->get_last_error() == NSAPI_ERROR_OK) {
+    err = _at->at_cmd_discard("+CFUN", "=4");
+    if (err == NSAPI_ERROR_OK) {
         _at->at_cmd_discard("E0", ""); // echo off
         _at->at_cmd_discard("+CMEE", "=1"); // verbose responses
         config_authentication_parameters();
-        _at->at_cmd_discard("+CFUN", "=1"); // set full functionality
+        err = _at->at_cmd_discard("+CFUN", "=1"); // set full functionality
     }
 #endif
 
-    return _at->unlock_return_error();
+    return err;
 }
 
 nsapi_error_t UBLOX_AT::config_authentication_parameters()
diff --git a/features/cellular/framework/targets/UBLOX/AT/UBLOX_AT_CellularContext.cpp b/features/cellular/framework/targets/UBLOX/AT/UBLOX_AT_CellularContext.cpp
index 715143cdb0..04c049e6fe 100644
--- a/features/cellular/framework/targets/UBLOX/AT/UBLOX_AT_CellularContext.cpp
+++ b/features/cellular/framework/targets/UBLOX/AT/UBLOX_AT_CellularContext.cpp
@@ -113,11 +113,13 @@ nsapi_error_t UBLOX_AT_CellularContext::define_context()
         return err;
     }
 
+    _at.lock();
     _at.cmd_start_stop("+UPSND", "=", "%d%d", PROFILE, 8);
     _at.resp_start("+UPSND:");
     _at.skip_param(2);
     active = _at.read_int();
     _at.resp_stop();
+    _at.unlock();
 
     if (active == 0) {
         // If the caller hasn't entered an APN, try to find it
@@ -193,11 +195,13 @@ bool UBLOX_AT_CellularContext::activate_profile(const char *apn,
                 Timer t1;
                 t1.start();
                 while (!(t1.read() >= 180)) {
+                    _at.lock();
                     _at.cmd_start_stop("+UPSND", "=", "%d%d", PROFILE, 8);
                     _at.resp_start("+UPSND:");
                     _at.skip_param(2);
                     _at.read_int() ? activated = true : activated = false;
                     _at.resp_stop();
+                    _at.unlock();
 
                     if (activated) {  //If context is activated, exit while loop and return status
                         break;