diff --git a/utils/json_codec_test.go b/utils/json_codec_test.go
index 791a68b1e..4596c33ff 100644
--- a/utils/json_codec_test.go
+++ b/utils/json_codec_test.go
@@ -24,6 +24,7 @@ import (
 	"fmt"
 	"io"
 	"net/rpc"
+	"reflect"
 	"testing"
 )
 
@@ -145,23 +146,26 @@ func TestJSONCodecReadRequestHeader2(t *testing.T) {
 }
 
 func TestJSONReadRequestBody(t *testing.T) {
-	tests := []struct{
-		name string
-		arg any 
-		exp error
-		params bool
+
+	tests := []struct {
+		name    string
+		arg     any
+		exp     string
+		params  bool
+		isApier bool
 	}{
 		{
-			name: "nil argument",
-			arg: nil,
-			exp: nil,
-			params: false,
+			name:    "nil argument",
+			arg:     nil,
+			params:  false,
+			isApier: false,
 		},
 		{
-			name: "check error missing param",
-			arg: "test",
-			exp: errMissingParams,
-			params: true,
+			name:    "check error missing param",
+			arg:     "test",
+			exp:     "jsonrpc: request body missing params",
+			params:  true,
+			isApier: false,
 		},
 	}
 
@@ -173,21 +177,256 @@ func TestJSONReadRequestBody(t *testing.T) {
 			s := NewCustomJSONServerCodec(conn)
 			sj := s.(*jsonServerCodec)
 
-			if tt.params {
-				sj.req.Params = nil
+			if !tt.params {
+				jm, _ := json.RawMessage.MarshalJSON([]byte(`{
+					"method": "ApierV.Method",
+					"params": [{
+						"TPid": "test"
+					}],
+					"id": 0
+				}`))
+				js := json.RawMessage(jm)
+				sj.req.Params = &js
+			}
+			if tt.isApier {
+				sj.req.isApier = true
 			}
 
-			err := s.ReadRequestBody(tt.arg)
+			rcv := s.ReadRequestBody(tt.arg)
 
-			if err != nil {
-				if err.Error() != tt.exp.Error() {
-					t.Errorf("recived %s, expected %s", err, tt.exp)
+			if rcv != nil {
+				if rcv.Error() != tt.exp {
+					t.Errorf("recived %s, expected %s", rcv, tt.exp)
 				}
 			}
 		})
 	}
 }
 
+func TestJSONReadRequestBody2(t *testing.T) {
+	conn := &bufferClose{
+		Buffer: &bytes.Buffer{},
+	}
+	s := NewCustomJSONServerCodec(conn)
+	sj := s.(*jsonServerCodec)
+
+	b, _ := json.Marshal([1]any{&CGREvent{Tenant: "cgrates.org"}})
+	js := json.RawMessage(b)
+	sj.req.Params = &js
+
+	sj.req.isApier = true
+
+	args := &MethodParameters{
+		Method:     "test",
+		Parameters: [1]any{&CGREvent{Tenant: "cgrates.net"}},
+	}
+	rcv := s.ReadRequestBody(args)
+
+	if rcv != nil {
+		t.Errorf("recived %v, expected %v", rcv, nil)
+	}
+
+	a := args.Parameters
+	if a.(map[string]any)[Tenant] != "cgrates.org" {
+		t.Errorf("expected %s, recived %s", args.Parameters.(*CGREvent).Tenant, "cgrates.org")
+	}
+}
+
+func TestJSONReadRequestBody3(t *testing.T) {
+	conn := &bufferClose{
+		Buffer: &bytes.Buffer{},
+	}
+	s := NewCustomJSONServerCodec(conn)
+	sj := s.(*jsonServerCodec)
+
+	b, _ := json.Marshal([1]any{&CGREvent{Tenant: "cgrates.org"}})
+	js := json.RawMessage(b)
+	sj.req.Params = &js
+
+	sj.req.isApier = false
+
+	args := &MethodParameters{
+		Method:     "test",
+		Parameters: [1]any{&CGREvent{Tenant: "cgrates.net"}},
+	}
+	rcv := s.ReadRequestBody(args)
+
+	if rcv != nil {
+		t.Errorf("recived %v, expected %v", rcv, nil)
+	}
+
+	a := args.Parameters.([1]any)
+	if a[0].(*CGREvent).Tenant != "cgrates.net" {
+		t.Errorf("expected %s, recived %s", a[0].(*CGREvent).Tenant, "cgrate.net")
+	}
+}
+
+
+/*
+- NewCustomJSONServerCodec
+- defer Close
+- ReadRequestHeader
+- check whether c.req was populated correctly
+- check whether c.seq was incremented
+- check whether c.req.Id was added to c.pending array
+- ReadRequestBody
+- check if x.Parameters was properly modified
+- WriteResponse
+- check if the rpc.Response is populated correctly
+*/
+func TestJSONCodecOK(t *testing.T) {
+	//Create server
+	conn := &bufferClose{
+		Buffer: &bytes.Buffer{},
+	}
+	s := NewCustomJSONServerCodec(conn)
+	c := s.(*jsonServerCodec)
+
+
+	defer s.Close()
+
+	//ReadRequesHeader
+	rr := rpc.Request{
+		ServiceMethod: "Service.Method",
+		Seq:           1,
+	}
+
+	conn.Write([]byte(`{
+		"method": "ApierV.Method",
+		"params": [{
+			"TPid": "test"
+		}],
+		"id": 0
+	}`))
+
+	err := s.ReadRequestHeader(&rr)
+	if err != nil {
+		t.Error(err)
+	}
+
+	if c.req.Method != "ApierV.Method" {
+		t.Errorf("received %v, expected %v", c.req.Method, "ApierV.Method")
+	}
+
+	exp := json.RawMessage([]byte{48})
+	rcv := *c.pending[1]
+	if !reflect.DeepEqual(rcv, exp) {
+		t.Errorf("received %v, expected %v", rcv, exp)
+	}
+
+	if c.seq != 1 {
+		t.Errorf("received %v, expected %v", c.seq, 1)
+	}
+
+	//ReadRequestBody
+	b, _ := json.Marshal([1]any{&CGREvent{Tenant: "cgrates.org"}})
+	js := json.RawMessage(b)
+	c.req.Params = &js
+
+	c.req.isApier = true
+
+	args := &MethodParameters{
+		Method:     "test",
+		Parameters: [1]any{&CGREvent{Tenant: "cgrates.net"}},
+	}
+	err = s.ReadRequestBody(args)
+
+	if err != nil {
+		t.Errorf("received %v, expected %v", err, nil)
+	}
+
+	a := args.Parameters
+	if a.(map[string]any)[Tenant] != "cgrates.org" {
+		t.Errorf("expected %s, received %s", args.Parameters.(*CGREvent).Tenant, "cgrates.org")
+	}
+
+	//WriteResponse
+	res := rpc.Response{
+		Seq: 1,
+	}
+	err = c.WriteResponse(&res, "test")
+	if err != nil {
+		t.Error(err)
+	}
+
+	mp := make(map[string]any)
+	err = c.dec.Decode(&mp)
+	if err != nil {
+		t.Error(err)
+	}
+
+	if mp["error"] != nil || 
+	mp["result"] != "test" || 
+	mp["id"] != 0. {
+		t.Error("unexpected reply", mp)
+	}
+}
+
+func TestJSONCodecWriteResponse(t *testing.T) {
+	conn := &bufferClose{
+		Buffer: &bytes.Buffer{},
+	}
+	s := NewCustomJSONServerCodec(conn)
+	c := s.(*jsonServerCodec)
+
+	defer s.Close()
+
+	res := rpc.Response{
+		Seq: 1,
+	}
+	err := c.WriteResponse(&res, "test")
+	if err.Error() != "invalid sequence number in response" {
+		t.Error(err)
+	}
+}
+
+func TestJSONCodecWriteResponse2(t *testing.T) {
+	conn := &bufferClose{
+		Buffer: &bytes.Buffer{},
+	}
+	s := NewCustomJSONServerCodec(conn)
+	c := s.(*jsonServerCodec)
+
+	conn.Write([]byte(`{
+		"method": "ApierV.Method",
+		"params": [{
+			"TPid": "test"
+		}]
+	}`))
+
+	defer s.Close()
+
+	rr := rpc.Request{
+		ServiceMethod: "Service.Method",
+		Seq:           1,
+	}
+	err := s.ReadRequestHeader(&rr)
+	if err != nil {
+		t.Error(err)
+	}
+
+	res := rpc.Response{
+		Seq: 1,
+		Error: "error", 
+	}
+	err = c.WriteResponse(&res, "test")
+	if err != nil {
+		t.Error(err)
+	}
+
+	mp := make(map[string]any)
+	err = c.dec.Decode(&mp)
+	if err != nil {
+		t.Error(err)
+	}
+
+	if mp["error"] != "error" || 
+	mp["result"] != nil || 
+	mp["id"] != nil {
+		t.Error("unexpected reply", mp)
+	}
+}
+
 func TestJSONCodecClose(t *testing.T) {
 	conn := &bufferClose{
 		Buffer: &bytes.Buffer{},