diff --git a/apier/v1/concreqs_it_test.go b/apier/v1/concreqs_it_test.go
index 088bc0788..abc2e4c3a 100644
--- a/apier/v1/concreqs_it_test.go
+++ b/apier/v1/concreqs_it_test.go
@@ -21,8 +21,13 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>
 package v1
 
 import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"net/http"
 	"net/rpc"
 	"path"
+	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -45,6 +50,8 @@ var (
 		testConcReqsRPCConn,
 		testConcReqsBusyAPIs,
 		testConcReqsQueueAPIs,
+		testConcReqsOnHTTPBusy,
+		testConcReqsOnHTTPQueue,
 		testConcReqsKillEngine,
 	}
 )
@@ -113,14 +120,17 @@ func testConcReqsBusyAPIs(t *testing.T) {
 	}
 	var failedAPIs int
 	wg := new(sync.WaitGroup)
+	lock := new(sync.Mutex)
 	for i := 0; i < 5; i++ {
 		wg.Add(1)
 		go func() {
 			var resp string
 			if err := concReqsRPC.Call(utils.CoreSv1Sleep,
-				&SleepArgs{SleepTime: time.Duration(10 * time.Millisecond)},
+				&DurationArgs{DurationTime: time.Duration(10 * time.Millisecond)},
 				&resp); err != nil {
+				lock.Lock()
 				failedAPIs++
+				lock.Unlock()
 				wg.Done()
 				return
 			}
@@ -143,7 +153,7 @@ func testConcReqsQueueAPIs(t *testing.T) {
 		go func() {
 			var resp string
 			if err := concReqsRPC.Call(utils.CoreSv1Sleep,
-				&SleepArgs{SleepTime: time.Duration(10 * time.Millisecond)},
+				&DurationArgs{DurationTime: time.Duration(10 * time.Millisecond)},
 				&resp); err != nil {
 				wg.Done()
 				t.Error(err)
@@ -155,7 +165,67 @@ func testConcReqsQueueAPIs(t *testing.T) {
 	wg.Wait()
 }
 
+func testConcReqsOnHTTPBusy(t *testing.T) {
+	if concReqsConfigDIR != "conc_reqs_busy" {
+		t.SkipNow()
+	}
+	var fldAPIs int64
+	wg := new(sync.WaitGroup)
+	lock := new(sync.Mutex)
+	for i := 0; i < 5; i++ {
+		wg.Add(1)
+		go func(index int) {
+			resp, err := http.Post("http://localhost:2080/jsonrpc", "application/json", bytes.NewBuffer([]byte(fmt.Sprintf(`{"method": "CoreSv1.Sleep", "params": [{"DurationTime":10000000}], "id":%d}`, index))))
+			if err != nil {
+				wg.Done()
+				t.Error(err)
+				return
+			}
+			contents, err := ioutil.ReadAll(resp.Body)
+			if err != nil {
+				wg.Done()
+				t.Error(err)
+				return
+			}
+			resp.Body.Close()
+			if strings.Contains(string(contents), "denying request due to maximum active requests reached") {
+				lock.Lock()
+				fldAPIs++
+				lock.Unlock()
+			}
+			wg.Done()
+			return
+		}(i)
+	}
+	wg.Wait()
+	if fldAPIs < 2 {
+		t.Errorf("Expected at leat 2 APIs to wait")
+	}
+}
+
+func testConcReqsOnHTTPQueue(t *testing.T) {
+	if concReqsConfigDIR != "conc_reqs_queue" {
+		t.SkipNow()
+	}
+	wg := new(sync.WaitGroup)
+	for i := 0; i < 5; i++ {
+		wg.Add(1)
+		go func(index int) {
+			_, err := http.Post("http://localhost:2080/jsonrpc", "application/json", bytes.NewBuffer([]byte(fmt.Sprintf(`{"method": "CoreSv1.Sleep", "params": [{"DurationTime":10000000}], "id":%d}`, index))))
+			if err != nil {
+				wg.Done()
+				t.Error(err)
+				return
+			}
+			wg.Done()
+			return
+		}(i)
+	}
+	wg.Wait()
+}
+
 func testConcReqsKillEngine(t *testing.T) {
+	time.Sleep(100 * time.Millisecond)
 	if err := engine.KillEngine(100); err != nil {
 		t.Error(err)
 	}
diff --git a/apier/v1/core.go b/apier/v1/core.go
index 80e2a965a..88cbbe096 100644
--- a/apier/v1/core.go
+++ b/apier/v1/core.go
@@ -50,13 +50,13 @@ func (cS *CoreSv1) Ping(ign *utils.CGREventWithArgDispatcher, reply *string) err
 	return nil
 }
 
-type SleepArgs struct {
-	SleepTime time.Duration
+type DurationArgs struct {
+	DurationTime time.Duration
 }
 
 // Sleep is used to test the concurrent requests mechanism
-func (cS *CoreSv1) Sleep(arg *SleepArgs, reply *string) error {
-	time.Sleep(arg.SleepTime)
+func (cS *CoreSv1) Sleep(arg *DurationArgs, reply *string) error {
+	time.Sleep(arg.DurationTime)
 	*reply = utils.OK
 	return nil
 }
diff --git a/cmd/cgr-tester/parallel/parallel.go b/cmd/cgr-tester/parallel/parallel.go
index e63746b61..b5c08416d 100644
--- a/cmd/cgr-tester/parallel/parallel.go
+++ b/cmd/cgr-tester/parallel/parallel.go
@@ -33,8 +33,8 @@ func main() {
 	log.Print("Start!")
 	var wg sync.WaitGroup
 	for i := 1; i < 1002; i++ {
+		wg.Add(1)
 		go func(index int) {
-			wg.Add(1)
 			resp, err := http.Post("http://localhost:2080/jsonrpc", "application/json", bytes.NewBuffer([]byte(fmt.Sprintf(`{"method": "APIerSv1.SetAccount","params": [{"Tenant":"reglo","Account":"100%d","ActionPlanId":"PACKAGE_NEW_FOR795", "ReloadScheduler":false}], "id":%d}`, index, index))))
 			if err != nil {
 				log.Print("Post error: ", err)